Update upgrade documentation to specify requirement for hetzner-k3s v…

…2.2.3 or higher

docs/Upgrading_a_cluster_from_1x_to_2x.md

@@ -2,15 +2,15 @@
 
 The v1 version of hetzner-k3s is quite old and hasn't been supported for a while, but I know that some people haven't upgraded to v2 because until now there wasn't a straightforward process to do this.
 
-This migration is now possible and straightforward provided you follow these instructions carefully and are patient. The migration also allows you to replace deprecated instance types (series `CX`) with new instance types.
+This migration is now possible and straightforward provided you follow these instructions carefully and are patient. The migration also allows you to replace deprecated instance types (series `CX`) with new instance types. This migration requires hetzner-k3s v2.2.3 or higher.
 
 ## Prerequisites
 
 - [ ] I recommend you install the [hcloud utility](https://github.com/hetznercloud/cli) to more easily/quickly delete old masters
 
 ## Upgrading configuration and first steps
 
-- [ ] ==Backup apps and data==
+- [ ] ==Backup apps and data== - like with all migrations, there is some risk involved, so be prepared in case something doesn't go according to the plan
 - [ ] ==Backup kubeconfig and old config file==
 - [ ] Uninstall the System Upgrade Controller
 - [ ] Create resolv file on existing nodes, either manually or automate it with the `hcloud` CLI