site-wide: Generate site content with a maintenance script.

When OVN 23.09 is released, we also will begin making more frequent
point-releases of all other supported branches. Updating the website by hand
for each release would be time-consuming and error-prone.

This change uses a website update script to generate the website content. The
script can be used for generating content for a new release or for updating
content for previous releases, since the script re-generates content from
scratch instead of actually updating the content.

src/content/releases/20.03.md

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++++
+title = "20.03"
+[_build]
+  list = 'never'
+
++++
+
+## OVN 20.03 
+
+OVN 20.03 was initially released on 2 March, 2020. 
+This version of OVN is no longer supported. Support ended on 2 March, 2023.
+
+### v20.03.2
+v20.03.2 was released on 12 April, 2021.
+
+[Github link](https://github.com/ovn-org/ovn/releases/tag/v20.03.2)
+
+Release Notes:
+```
+OVN v20.03.2 - 12 Apr 2021
+--------------------------
+   - Bug fixes
+
+
+```
+[Changelog](../changelog_v20.03.2)
+
+### v20.03.1
+v20.03.1 was released on 11 June, 2020.
+
+[Github link](https://github.com/ovn-org/ovn/releases/tag/v20.03.1)
+
+Release Notes:
+```
+OVN v20.03.1 - 09 Jun 2020
+--------------------------
+
+
+```
+[Changelog](../changelog_v20.03.1)
+
+### v20.03.0
+v20.03.0 was released on 2 March, 2020.
+
+[Github link](https://github.com/ovn-org/ovn/releases/tag/v20.03.0)
+
+Release Notes:
+```
+OVN v20.03.0 - 28 Feb 2020
+---------------------
+   - OVN was split out from the OVS repository and is now released
+     independently.
+   - Added IPv6 NAT support for OVN routers.
+   - Added Stateless Floating IP support in OVN.
+   - Added Forwarding Group support in OVN.
+   - Added support for MLD Snooping and MLD Querier.
+   - Added support for ECMP routes in OVN router.
+
+   - OVN Interconnection:
+     * Support for L3 interconnection of multiple OVN deployments with tunnels
+       managed by OVN.  See instructions in
+       Documentation/tutorials/ovn-interconnection.rst.
+
+
+```
+[Changelog](../changelog_v20.03.0)

src/content/releases/20.06.md

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++++
+title = "20.06"
+[_build]
+  list = 'never'
+
++++
+
+## OVN 20.06 
+
+OVN 20.06 was initially released on 9 June, 2020. 
+This version of OVN is no longer supported. Support ended on 9 June, 2021.
+
+### v20.06.3
+v20.06.3 was released on 12 April, 2021.
+
+[Github link](https://github.com/ovn-org/ovn/releases/tag/v20.06.3)
+
+Release Notes:
+```
+OVN v20.06.3 - 12 Apr 2021
+--------------------------
+   - Bug fixes
+
+
+```
+[Changelog](../changelog_v20.06.3)
+
+### v20.06.2
+v20.06.2 was released on 21 August, 2020.
+
+[Github link](https://github.com/ovn-org/ovn/releases/tag/v20.06.2)
+
+Release Notes:
+```
+OVN v20.06.2 - 21 Aug 2020
+--------------------------
+   - ovn-controller incremental processing bug fixes.
+   - Scale improvements which reduce logical flows to limit
+     ARP/NS broadcast domain and to optionally disable neighbor
+     learning from ARP request/IPv6 Neighbor Solicitation.
+
+
+```
+[Changelog](../changelog_v20.06.2)
+
+### v20.06.1
+v20.06.1 was released on 8 July, 2020.
+
+[Github link](https://github.com/ovn-org/ovn/releases/tag/v20.06.1)
+
+Release Notes:
+```
+OVN v20.06.1 - 08 Jul 2020
+--------------------------
+
+
+```
+[Changelog](../changelog_v20.06.1)
+
+### v20.06.0
+v20.06.0 was released on 9 June, 2020.
+
+[Github link](https://github.com/ovn-org/ovn/releases/tag/v20.06.0)
+
+Release Notes:
+```
+OVN v20.06.0 - 08 Jun 2020
+--------------------------
+   - Added support for external_port_range in NAT table.
+   - ovn-controller no longer monitor the external_ids column from
+     the Chassis table. This was done to avoid having to do a flow
+     recalculation every time external systems wrote to this column. The
+     chassis configuration has now being moved to a new column called
+     "other_config". As a note, the configurations are still be written to
+     the external_ids column (but no longer triggers an alert) to
+     keep the backward compatibility with current systems that may be
+     reading it from that column but, this behavior will be removed
+     in the future.
+   - Added IPv6 Prefix Delegation support in OVN.
+   - OVN now uses OpenFlow 1.5.
+   - Added support to choose selection methods - dp_hash or
+     hash (with specified hash fields) for OVN load balancer
+     backend selection. This is incompatible with older versions.
+     Care should be taken while upgrading as the existing
+     load balancer traffic will be affected if ovn-controllers
+     are not stopped before uprading northd services.
+   - Added limited support for logical switches with multiple localnet ports.
+     The feature requires that no chassis has two or more physical networks
+     with localnet ports that belong to the same logical switch mapped. Routing
+     between the ports to be implemented by fabric.
+
+   - OVN Interconnection:
+     * Support for L3 interconnection of multiple OVN deployments with tunnels
+       managed by OVN.  See instructions in
+       Documentation/tutorials/ovn-interconnection.rst.
+
+
+
+```
+[Changelog](../changelog_v20.06.0)

src/content/releases/20.09.md

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++++
+title = "20.09"
+[_build]
+  list = 'never'
+
++++
+
+## OVN 20.09 
+
+OVN 20.09 was initially released on 28 September, 2020. 
+This version of OVN is no longer supported. Support ended on 28 September, 2021.
+
+### v20.09.0
+v20.09.0 was released on 28 September, 2020.
+
+[Github link](https://github.com/ovn-org/ovn/releases/tag/v20.09.0)
+
+Release Notes:
+```
+OVN v20.09.0 - 28 Sep 2020
+--------------------------
+   - Added packet marking support for traffic routed with
+     a routing policy.
+   - Added DHCPINFORM and DHCPRELEASE support in native
+     OVN DHCPv4 responder.
+   - Added support for DHCP domain search option (119) in native
+     OVN DHCPv4 responder.
+   - The nb_cfg column from the Chassis table in the OVN Southbound
+     database has been deprecated and is no longer updated. A new table
+     called Chassis_Private now contains the nb_cfg column which is updated
+     by incrementing the value in the NB_Global table, CMSes relying on
+     this mechanism should update their code to use this new table.
+   - Added support for external ip based NAT. Now, besides the logical ip,
+     external ips will also decide if a packet will be NATed or not.
+   - Added support for VXLAN encapsulation (not just for ramp/VTEP switches).
+
+
+```
+[Changelog](../changelog_v20.09.0)

src/content/releases/20.12.md

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++++
+title = "20.12"
+[_build]
+  list = 'never'
+
++++
+
+## OVN 20.12 
+
+OVN 20.12 was initially released on 17 December, 2020. 
+This version of OVN is no longer supported. Support ended on 17 December, 2021.
+
+### v20.12.0
+v20.12.0 was released on 17 December, 2020.
+
+[Github link](https://github.com/ovn-org/ovn/releases/tag/v20.12.0)
+
+Release Notes:
+```
+OVN v20.12.0 - 18 Dec 2020
+--------------------------
+   - The "datapath" argument to ovn-trace is now optional, since the
+     datapath can be inferred from the inport (which is required).
+   - The obsolete "redirect-chassis" way to configure gateways has been
+     removed.  See ovn-nb(5) for advice on how to update your config if needed.
+   - Add IPv4 iPXE support introducing "bootfile_name_alt" option to ovn dhcp
+     server.
+   - Support other_config:vlan-passthru=true to allow VLAN tagged incoming
+     traffic.
+   - Propagate currently processed SB_Global.nb_cfg in ovn-controller to the
+     local OVS DB integration bridge external_ids:ovn-nb-cfg.
+   - Support version pinning between ovn-northd and ovn-controller as an
+     option. If the option is enabled and the versions don't match,
+     ovn-controller will not process any DB changes.
+   - Add "fair" column in Meter table to allow multiple ACL logs to use the
+     same Meter while being rate-limited independently.
+   - New configuration option for northd 'options:use_logical_dp_groups=true'
+     to enable combining of logical flows by logical datapath.  This should
+     significantly decrease size of a Southbound DB.  However, in some cases,
+     it could have performance penalty for ovn-controller.  Disabled by
+     default.
+
+
+```
+[Changelog](../changelog_v20.12.0)

src/content/releases/21.03.md

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++++
+title = "21.03"
+[_build]
+  list = 'never'
+
++++
+
+## OVN 21.03 
+
+OVN 21.03 was initially released on 12 March, 2021. 
+This version of OVN is no longer supported. Support ended on 12 March, 2022.
+
+### v21.03.0
+v21.03.0 was released on 12 March, 2021.
+
+[Github link](https://github.com/ovn-org/ovn/releases/tag/v21.03.0)
+
+Release Notes:
+```
+OVN v21.03.0 - 12 Mar 2021
+-------------------------
+  - Support ECMP multiple nexthops for reroute router policies.
+   - BFD protocol support according to RFC880 [0]. Introduce next-hop BFD
+     availability check for OVN static routes.
+     [0] https://tools.ietf.org/html/rfc5880)
+  - Change the semantic of the "Logical_Switch_Port.up" field such that it is
+    set to "true" only when all corresponding OVS openflow operations have
+    been processed.  This also introduces a new "OVS.Interface.external-id",
+    "ovn-installed".  This external-id is set by ovn-controller only after all
+    openflow operations corresponding to the OVS interface being added have
+    been processed.
+  - ovn-ctl: Added new command line argument '--ovsdb-disable-file-column-diff'
+    to support ovsdb-server upgrades from version 2.14 and earlier to
+    2.15 and later.  See ovsdb(7) for more details.
+  - Add a new option to Load_Balancer.options, "hairpin_snat_ip", to allow
+    users to explicitly select which source IP should be used for load
+    balancer hairpin traffic.
+  - ovn-controller: Add configuration knobs, through OVS external-id
+    "ovn-limit-lflow-cache" and "ovn-memlimit-lflow-cache-kb", to allow
+    enforcing a limit for the size of the logical flow cache based on
+    maximum number of entries and/or memory usage.
+  - ovn-controller: Add lflow cache related memory reports.
+
+
+```
+[Changelog](../changelog_v21.03.0)

src/content/releases/21.06.md

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++++
+title = "21.06"
+[_build]
+  list = 'never'
+
++++
+
+## OVN 21.06 
+
+OVN 21.06 was initially released on 18 June, 2021. 
+This version of OVN is no longer supported. Support ended on 18 June, 2022.
+
+### v21.06.0
+v21.06.0 was released on 18 June, 2021.
+
+[Github link](https://github.com/ovn-org/ovn/releases/tag/v21.06.0)
+
+Release Notes:
+```
+OVN v21.06.0 - 18 Jun 2021
+-------------------------
+  - ovn-northd-ddlog: New implementation of northd, based on DDlog.  This
+    implementation is incremental, meaning that it only recalculates what is
+    needed for the southbound database when northbound changes occur.  It is
+    expected to scale better than the C implementation, for large deployments.
+    (This may take testing and tuning to be effective.)  This version of OVN
+    requires DDLog 0.38.
+  - Introduce ovn-controller incremental processing engine statistics
+  - Introduced parallel processing in ovn-northd with the NB_Global config option
+    'use_parallel_build' to enable it.  It is disabled by default.
+  - Support vlan-passthru mode for tag=0 localnet ports.
+  - Support custom 802.11ad EthType for localnet ports.
+  - Add a new NB Global option - use_ct_inv_match with the default value of
+    true. If this is set to false, then the logical field - "ct.inv" will not
+    be used in the logical flow matches.  CMS can consider setting this to
+    false, if they want to use smart NICs which don't support offloading
+    datapath flows with this field used.
+  - Introduce a new "allow-stateless" ACL verb to always bypass connection
+    tracking. The existing "allow" verb behavior is left intact.
+  - Added support in native DNS to respond to PTR request types.
+  - ovn-nbctl daemon mode is no longer considered experimental.
+  - Utilities:
+    * ovn-nbctl daemon mode is no longer considered experimental.
+    * ovn-sbctl now also supports daemon mode.
+  - Added support in native DNS to respond to PTR request types.
+  - New --dry-run option for ovn-northd and ovn-northd-ddlog.
+
+
+```
+[Changelog](../changelog_v21.06.0)