Add RELEASENOTES.rst
Add RELEASENOTES.rst

Add a file for tracking our release notes, this can be updated whenever
major new features get added.

Change-Id: I8d56cb3f12e945baf8738f16e84c21868ff10e42

openstack/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals