Added index.rst in each sub-directory

The doc migration spec requires each sub directory
to have an index page which could be directly
referenced in the main openstack documentation under
the topic specific pages, along with other projects.

This patch validates that and adds new files where
they are absent.

Change-Id: I180952857db758482fd767aa9f5cf6343fec9c42

doc/source/configuration/index.rst

@@ -0,0 +1,13 @@
+==============================
+Keystone Configuration Options
+==============================
+
+This section provides a list of all possible options and
+sample files for keystone configuration.
+
+.. toctree::
+    :maxdepth: 2
+
+    config-options.rst
+    policy.rst
+    samples/index.rst

doc/source/configuration/policy.rst

@@ -2,6 +2,9 @@
 Policy configuration
 ====================
 
+Configuration
+~~~~~~~~~~~~~
+
 The following is an overview of all available policies in Keystone. For a sample
 configuration file, refer to :doc:`/sample_files/sample_policy`.
 

doc/source/index.rst

@@ -94,17 +94,15 @@ Administrator Guides
 .. toctree::
     :maxdepth: 2
 
-    admin/identity-management.rst
+    admin/index.rst
 
 Configuration Options
 ~~~~~~~~~~~~~~~~~~~~~
 
 .. toctree::
-    :maxdepth: 1
+    :maxdepth: 2
 
-    configuration/config-options.rst
-    configuration/policy.rst
-    configuration/samples/index.rst
+    configuration/index.rst
 
 API Documentation
 ~~~~~~~~~~~~~~~~~