Configure ceilometer coordination backend_url

Add ability to configure ceilometer coordination backend_url from
coordination_backend:redis pillar if enabled

Related-Prod: PROD-29126

Change-Id: I97acb85ae93300102d50dbbd9eb89597b6f1e666
diff --git a/README.rst b/README.rst
index 0bc8d4b..ae4d984 100644
--- a/README.rst
+++ b/README.rst
@@ -369,7 +369,24 @@
         cert_file: (certificate path)
         key_file: (key path)
 
+Setup redis coordination_backend url:
+---------------------------
+.. code-block:: yaml
 
+    ceilometer:
+      server:
+        coordination_backend:
+          engine: redis
+          redis:
+            password: pswd
+            user: openstack
+            db: '0'
+            sentinel:
+              host: 127.0.0.1
+              master_name: master_1
+              fallback:
+                - host: 127.0.1.1
+                - host: 127.0.2.1
 
 More Information
 ================