Ussuri contributor docs community goal
Ussuri contributor docs community goal

- Updated CONTRIBUTING.rst per goal guidelines
- The repository does not have docs, so rely on main sahara docs

Change-Id: I1317b2acdbd3ae56bb9f6db305e6404969da3644

openstack/sahara-extra,openstack/sahara-extra,openstack/sahara-extra,openstack/sahara-extra