Add release notes link in README
Add release notes link in README

Change-Id: I8d67b14c0137b108970d004a8a18129bb58ed606

noironetworks/neutron,mahak/neutron,huntxu/neutron,noironetworks/neutron,mahak/neutron,openstack/neutron,mahak/neutron,huntxu/neutron,openstack/neutron,openstack/neutron