Add example configuration for main database

Author: rutgerw

files/gitlab-config-template/gitlab.rb.template

@@ -761,6 +761,8 @@ external_url 'GENERATED_EXTERNAL_URL'
 
 ### Gitlab decomposed database settings
 ###! Docs: https://docs.gitlab.com/omnibus/settings/database.html
+# gitlab_rails['databases']['main']['db_database'] = 'gitlabhq_production'
+# gitlab_rails['databases']['main']['database_tasks'] = true
 # gitlab_rails['databases']['ci']['enable'] = true
 # gitlab_rails['databases']['ci']['db_database'] = 'gitlabhq_production'
 # gitlab_rails['databases']['ci']['database_tasks'] = false