Merge branch 'docs/geo-update-pg-hba-secondary' into 'master'

Docs - Update pg_hba example for secondary Geo node

See merge request gitlab-org/gitlab!29650

doc/administration/geo/replication/external_database.md

@@ -75,8 +75,19 @@ hot_standby = on
 
 ### Manually configure the replica database
 
-Make the following configuration changes manually to your `postgresql.conf`
-of external replica database:
+Make the following configuration changes manually to your `pg_hba.conf` and `postgresql.conf`
+of your external replica database and ensure that you restart PostgreSQL afterwards
+for the changes to take effect:
+
+```plaintext
+##
+## Geo Secondary Role
+## - pg_hba.conf
+##
+host    all         all               <trusted secondary IP>/32     md5
+host    replication gitlab_replicator <trusted secondary IP>/32     md5
+host    all         all               <trusted primary IP>/24       md5
+```
 
 ```plaintext
 ##