fix release note link in README.rst

Change-Id: I8ad007a37225b61f598c196c33150ee6772ee6ae
Closes-Bug: #1571130

doc/source/index.rst

@@ -51,6 +51,7 @@ Appendix
 .. toctree::
    :maxdepth: 1
 
+   releasenotes/index
    glossary
    api/index
 

doc/source/releasenotes/index.rst

@@ -0,0 +1,29 @@
+..
+      Copyright (c) 2016 Hewlett Packard Enterprise Development Company, L.P.
+
+      Licensed under the Apache License, Version 2.0 (the "License"); you may
+      not use this file except in compliance with the License. You may obtain
+      a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+      WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+      License for the specific language governing permissions and limitations
+      under the License.
+
+============================
+ Release Notes
+============================
+
+.. toctree::
+   :hidden:
+
+* `Liberty`_
+
+Since Mitaka development cycle, we start to host release notes on:
+`Aodh Release Notes`_
+
+.. _Liberty: https://wiki.openstack.org/wiki/ReleaseNotes/Liberty#OpenStack_Telemetry_.28Ceilometer.29
+.. _Aodh Release Notes: http://docs.openstack.org/releasenotes/aodh/