docs(customizing_deis): clarify usage of registrationMode

Author: Joshua-Anderson

docs/customizing_deis/controller_settings.rst

@@ -109,9 +109,33 @@ server
     every application or scaling them down and up.
     The change is only detected when a container unit is deployed.
 
+Changing the Registration Mode
+------------------------------
+
+By default, anybody can register a user with the Deis controller.
+However, this is often undesirable from a security point of view.
+
+Deis supports configuring the registration mode through the ``registrationMode`` setting.
+
+Registration Modes
+^^^^^^^^^^^^^^^^^^
+========== =========================================================
+mode       description
+========== =========================================================
+enabled    Default. Anybody can register a user with the controller.
+disabled   Nobody can register a user with the controller.
+admin_only Only admins can register a user with the controller.
+========== =========================================================
+
+This will set the registration mode to admin_only.
+
+.. code-block:: console
+
+    $ deisctl config controller set registrationMode="admin_only"
+
 Using a LDAP Auth
 -----------------
-Deis Controller supports Single Sign On access control, for now Deis is able to authenticate using LDAP or Active Directory.
+The Deis controller supports Single Sign On access control, for now Deis is able to authenticate using LDAP or Active Directory.
 
 Settings used by LDAP
 ^^^^^^^^^^^^^^^^^^^^^

docs/managing_deis/operational_tasks.rst

@@ -34,12 +34,17 @@ You can use the ``deis perms`` command to promote a user to an administrator:
 Disabling user registration
 ---------------------------
 
-You can disallow all users from registering with the Deis cluster using the following command:
+You can disable user registration for everybody except admins:
 
 .. code-block:: console
 
-    $ deisctl config controller set registrationEnabled=0
+    $ deisctl config controller set registrationMode="admin_only"
 
+If you want to entirely disable user registration:
+
+.. code-block:: console
+
+    $ deisctl config controller set registrationMode="disabled"
 
 Re-issuing User Authentication Tokens
 -------------------------------------