Deprecate UI install instructions

Tripleo-ui has been removed as of Train. But we should keep the docs
around a bit longer as we don't branch tripleo-docs.

Change-Id: Iaaa3f6ece433401d696fe7f5d29d916c5c3d0c26

doc/source/install/advanced_deployment/multiple_overclouds.rst

@@ -26,7 +26,7 @@ Deploy the Undercloud :doc:`as usual <../installation/installation>`.
 First Overcloud
 ---------------
 
-The first Overcloud can be deployed as usual using the :doc:`cli <../basic_deployment/basic_deployment_cli>` or :doc:`UI <../basic_deployment/basic_deployment_ui>`.
+The first Overcloud can be deployed as usual using the :doc:`cli <../basic_deployment/basic_deployment_cli>`.
 
 Deploying Additional Overclouds
 -------------------------------

doc/source/install/deprecated/basic_deployment_ui.rst

@@ -1,7 +1,10 @@
 .. _basic-deployment-ui:
 
-Basic Deployment (UI)
-=====================
+(DEPRECATED) Basic Deployment (UI)
+==================================
+
+.. note:: The tripleo-ui is no longer available as of Stein. This documentation
+   is deprecated.
 
 This document will show you how to access the |project| UI and perform
 a simple deployment with some customizations. Validations are

doc/source/install/index.rst

@@ -10,7 +10,7 @@ TripleO Install Guide
   installation/installation
   advanced_deployment/undercloud_minion
   basic_deployment/basic_deployment_cli
-  basic_deployment/basic_deployment_ui
+  deprecated/basic_deployment_ui
   basic_deployment/tempest
   basic_deployment/tempest_plugins
   basic_deployment/os_tempest