Merge branch 'add_docker_registry_replication_options_to_gitlab_yml_template' into 'master'

Add Notification secret into gitlab.yml.template

See merge request gitlab-org/gitlab-ce!32532

config/gitlab.yml.example

@@ -431,6 +431,7 @@ production: &base
     # key: config/registry.key
     # path: shared/registry
     # issuer: gitlab-issuer
+    # notification_secret: '' # only set it when you use Geo replication feature without built-in Registry
     # Add notification settings if you plan to use Geo Replication for the registry
     # notifications: