Merge branch 'docs/create-gitlabhq-production-db-manually' into 'master'

Create the gitlabhq_production DB manually

See merge request gitlab-org/gitlab!40567

doc/administration/postgresql/external.md

@@ -11,8 +11,7 @@ If you use a cloud-managed service, or provide your own PostgreSQL instance:
 
 1. Set up PostgreSQL according to the
    [database requirements document](../../install/requirements.md#database).
-1. Set up a `gitlab` username with a password of your choice. The `gitlab` user
-   needs privileges to create the `gitlabhq_production` database.
+1. Set up a `gitlab` user with a password of your choice, create the `gitlabhq_production` database, and make the user an owner of the database. You can see an example of this setup in the [installation from source documentation](../../install/installation.md#6-database).
 1. If you are using a cloud-managed service, you may need to grant additional
    roles to your `gitlab` user:
    - Amazon RDS requires the [`rds_superuser`](https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Appendix.PostgreSQL.CommonDBATasks.html#Appendix.PostgreSQL.CommonDBATasks.Roles) role.