Add source code repository notes link to README
Add source code repository notes link to README

Change-Id: I7dcc8d85ed05fafbb86a042fa957065c7de66bb0

os-cloud/openstack-ansible-galera_server,os-cloud/openstack-ansible-galera_server,openstack/openstack-ansible-galera_server,openstack/openstack-ansible-galera_server