add collection retrieval strategy to doc

Signed-off-by: Loic Reyreaud <[email protected]>

developers/weaviate/config-refs/env-vars.md

@@ -113,6 +113,12 @@ default hostname has changed and a single node cluster believes there are suppos
 | `CLUSTER_HOSTNAME` | Hostname of a node. Always set this value if the default OS hostname might change over time. | `string` | `node1` |
 | `CLUSTER_JOIN` | The service name of the "founding" member node in a cluster setup | `string` | `weaviate-node-1:7100` |
 | `HNSW_STARTUP_WAIT_FOR_VECTOR_CACHE` | If `true`, vector cache prefill is synchronous when a node starts. The node reports ready to serve when the cache is hot. Defaults to `false`. Added in 1.24.20 and 1.25.5. | `boolean` | `false` |
+| `COLLECTION_RETRIEVAL_STRATEGY`| Possible values: `LeaderOnly`, `LocalOnly`, `LeaderOnMismatch`. Default: `LeaderOnly`. Changes the
+behavior of non-leader node in the cluster to retrieve the collection definition when a data requests needs it. By default it will always
+ask the leader (`LeaderOnly`) for the up-to-date definition. If your system can accept eventual consistency, this can be changed to
+`LocalOnly` to avoid unecessary traffic in the cluster. To only request the full definition when it has been updated use `LeaderOnMismatch`.
+This will make the follower node first check with the leader if the class has changed, and then request the up-to-date definition if
+necessary. | `string` | `LeaderOnly` |
 | `RAFT_ENABLE_FQDN_RESOLVER` | If `true`, use DNS lookup instead of memberlist lookup for Raft. Added in `v1.25.15`. ([Read more](../concepts/cluster.md#fqdn-for-node-discovery)) | `boolean` | `true` |
 | `RAFT_FQDN_RESOLVER_TLD` | The top-level domain to use for DNS lookup, in `[node-id].[tld]` format. Added in `v1.25.15`. ([Read more](../concepts/cluster.md#fqdn-for-node-discovery)) | `string` | `example.com` |
 | `RAFT_BOOTSTRAP_EXPECT` | The number of voter notes at bootstrapping time | `string - number` | `1` |