Add guidelines for release notes to devref

Starting from this cycle (and stable Liberty) we're using reno for
release notes. This commit adds guidelines on when a release note is
required to be added.

Change-Id: If5aa6ab8317ec2f4295d899a45f80f11504d2a2c

doc/source/devref/index.rst

@@ -53,6 +53,7 @@ Other Resources
    launchpad
    gerrit
    jenkins
+   releasenotes
 
 API Reference
 -------------

doc/source/devref/releasenotes.rst

@@ -0,0 +1,66 @@
+..
+      Copyright 2015 Intel Corporation
+      All Rights Reserved.
+
+      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
+=============
+
+The release notes for a patch should be included in the patch. If not, the
+release notes should be in a follow-on review.
+
+If the following applies to the patch, a release note is required:
+
+* Upgrades
+
+  * The deployer needs to take an action when upgrading
+  * A new config option is added that the deployer should consider changing
+    from the default
+  * A configuration option is deprecated or removed
+
+* Features
+
+  * A new feature or driver is implemented
+  * Feature is deprecated or removed
+  * Current behavior is changed
+
+* Bugs
+
+  * A security bug is fixed
+  * A long-standing or important bug is fixed
+
+* APIs
+
+  * The storage or backup driver interface changes
+  * REST API changes
+
+Cinder uses `reno <http://docs.openstack.org/developer/reno/usage.html>`_ to
+generate release notes. Please read the docs for details. In summary, use
+
+.. code-block:: bash
+
+  $ tox -e venv -- reno new <bug-,bp-,whatever>
+
+Then edit the sample file that was created and push it with your change.
+
+To see the results:
+
+.. code-block:: bash
+
+  $ git commit  # Commit the change because reno scans git log.
+
+  $ tox -e releasenotes
+
+Then look at the generated release notes files in releasenotes/build/html in
+your favorite browser.