Configure aodh coordination backend_url

Add ability to configure aodh coordination backend_url from
coordination_backend:redis pillar if defined

Related-Prod: PROD-29126

Change-Id: I5f9b98c472be31e6344b438515d4075a959c2c1d
diff --git a/README.rst b/README.rst
index 713026d..624468c 100644
--- a/README.rst
+++ b/README.rst
@@ -143,6 +143,25 @@
             strategy: ENCRYPT
             secret_key: secret
 
+Setup redis coordination_backend url:
+---------------------------
+.. code-block:: yaml
+
+    aodh:
+      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
+
 Development and testing
 =======================