Merge pull request #4143 from mdolian/master

docs(managing_deis): add section for registrationMode

Author: carmstrong

docs/managing_deis/production_deployments.rst

@@ -60,6 +60,15 @@ Back up data
 
 Backing up data regularly is recommended. See :ref:`backing_up_data` for steps.
 
+Change Registration Mode
+------------------------
+
+Changing the registration process is highly recommended in production.  By default, registrations for a
+new cluster are open to anyone with the proper URL.  Once the admin user has registered with a new cluster,
+it is recommended that you either turn off registrations entirely or enable the admin only registration feature.
+
+Please see the following documentation:  :ref:`controller_settings`
+
 Configure logging and monitoring
 --------------------------------