Adds docs note about using wildcard address for PG when setting up Geo

doc/administration/geo/replication/database.md

@@ -167,6 +167,11 @@ There is an [issue where support is being discussed](https://gitlab.com/gitlab-o
    corresponding to the given address. See [the PostgreSQL documentation](https://www.postgresql.org/docs/11/runtime-config-connection.html)
    for more details.
 
+   NOTE: **Note:**
+   If you need to use `0.0.0.0` or `*` as the listen_address, you will also need to add
+   `127.0.0.1/32` to the `postgresql['md5_auth_cidr_addresses']` setting, to allow Rails to connect through
+   `127.0.0.1`. For more information, see [omnibus-5258](https://gitlab.com/gitlab-org/omnibus-gitlab/-/issues/5258).
+
    Depending on your network configuration, the suggested addresses may not
    be correct. If your **primary** node and **secondary** nodes connect over a local
    area network, or a virtual network connecting availability zones like