Migrate backporting page from wiki

Change-Id: I9ce146e128bb0c40a809652494118f0e15c0fc8c

doc/source/backporting.rst

@@ -0,0 +1,26 @@
+Backporting
+===========
+
+This page documents Puppet OpenStack backport policy.
+
+Can be backported
+-----------------
+
+-  Critical and High bugs fixes, if reported in Launchpad.
+-  Features if they don't change anything in the stable interface and
+   only if backward compatibility is fully respected. Also if the
+   feature works for the OpenStack release where it's backported to.
+
+Cannot be backported
+--------------------
+
+-  Medium and Low bug fixes
+-  Features that break backward compatibility or change the existing
+   interface (default values or name of parameters).
+
+Merge Conflict
+--------------
+
+-  Explain in commit message what is conflicting and how it's resolved.
+-  Document the changes between master and stable branches in the code
+   or in the commit message.

doc/source/index.rst

@@ -12,6 +12,7 @@ OpenStack cloud deployments.
    deploy
    contribute
    new-module
+   backporting
    community
    mailing-list