Merge branch 'docs-patroni-rever-pg-upgrade' into 'master'

Update revert-pg-upgrade docs for Patroni cluster

See merge request gitlab-org/gitlab!44259

doc/administration/postgresql/replication_and_failover.md

@@ -1445,7 +1445,7 @@ Considering these, you should carefully plan your PostgreSQL upgrade:
    sudo gitlab-ctl pg-upgrade -V 12
    ```
 
-CAUTION: **Warning:**
+NOTE: **Note:**
 Reverting PostgreSQL upgrade with `gitlab-ctl revert-pg-upgrade` has the same considerations as
-`gitlab-ctl pg-upgrade`. It can be complicated and may involve deletion of the data directory.
-If you need to do that, please contact GitLab support.
+`gitlab-ctl pg-upgrade`. You should follow the same procedure by first stopping the replicas,
+then reverting the leader, and finally reverting the replicas.