Add CONTRIBUTING.rst
Add CONTRIBUTING.rst

There is no CONTRIBUTING.rst file, the patch will add it.

Change-Id: Ifcdc30b47b5fb668bbca2e974d8cff63a938addb

stackforge/networking-mlnx,openstack/networking-mlnx,stackforge/networking-mlnx,moshele/networking-mlnx,openstack/networking-mlnx,moshele/networking-mlnx-master