Update cinder policy management

Related: PROD-34318

Change-Id: I0c12b23f701d0961602c8b654bbf32292ad6e66f
diff --git a/README.rst b/README.rst
index 3261f4e..6b33e7a 100644
--- a/README.rst
+++ b/README.rst
@@ -1029,6 +1029,21 @@
             use_default_quota_class: true
             per_volume_size_limit: 100
 
+
+Change default service policy configuration:
+============================================
+
+.. code-block:: yaml
+
+    cinder:
+      controller:
+        policy:
+          context_is_admin: 'role:admin'
+          admin_or_owner:  'is_admin:True or project_id:%(project_id)s'
+          # Add key without value to remove line from policy.json
+          volume:create:
+
+
 Upgrades
 ========