Changes to cliff should be submitted for review via the Gerrit tool,
following the workflow documented at:

   http://wiki.openstack.org/GerritWorkflow

Pull requests submitted through GitHub will be ignored.

Bugs should be filed on Launchpad, not GitHub:

   https://bugs.launchpad.net/python-stevedore

Add contributing instructions for github mirrors
Add contributing instructions for github mirrors

Change-Id: I78ae4977b7f005e4b47aa736ed4594cd994fd3ca
