Update database.md Geo docs to clarify Postgres needs to be manually restarted
Related to https://gitlab.com/gitlab-org/omnibus-gitlab/issues/2797 and from Dmountney on Slack:
We currently no longer restart postgres for you on config change. https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/files/gitlab-config-template/gitlab.rb.template#L634