Migrate settings on a feature merged recently

Recently the support for domain drop-down menu at login was merged
into django_openstack_auth and the corresponding settings docs were
merged into horizon. This commit migrates the settings docs from
horizon as we recently moved django_openstack_auth settings into
the in-tree docuemnt.

Change-Id: Idc84a2535c1918079c6dcba09aef9110cf9be7df

1 files changed, 27 insertions, 0 deletions

diff --git a/doc/source/configuration/index.rst b/doc/source/configuration/index.rst
index b442a3f..26c272b 100644
--- a/doc/source/configuration/index.rst
+++ b/doc/source/configuration/index.rst
@@ -98,6 +98,33 @@ with Keystone V3. All entities will be created in the default domain.
    ``"cloud_admin": "rule:admin_required and domain_id:<your domain id>"``.
    This value must be the name of the domain whose ID is specified there.
 
+``OPENSTACK_KEYSTONE_DOMAIN_CHOICES``
+-------------------------------------
+
+.. versionadded:: 12.0.0(Pike)
+
+Default::
+
+        (
+          ('Default', 'Default'),
+        )
+
+If OPENSTACK_KEYSTONE_DOMAIN_DROPDOWN is enabled, this option can be used to
+set the available domains to choose from. This is a list of pairs whose first
+value is the domain name and the second is the display name.
+
+``OPENSTACK_KEYSTONE_DOMAIN_DROPDOWN``
+--------------------------------------
+
+.. versionadded:: 12.0.0(Pike)
+
+Default: ``False``
+Set this to True if you want available domains displayed as a dropdown menu on
+the login screen. It is strongly advised NOT to enable this for public clouds,
+as advertising enabled domains to unauthenticated customers irresponsibly
+exposes private information. This should only be used for private clouds where
+the dashboard sits behind a corporate firewall.
+
 ``OPENSTACK_KEYSTONE_MULTIDOMAIN_SUPPORT``
 ------------------------------------------