Releasenotes are version independent, so remove version/release display.
This is needed for new release notes publishing, see
I56909152975f731a9d2c21b2825b972195e48ee8 and the discussion starting
at
http://lists.openstack.org/pipermail/openstack-dev/2017-November/124480.html
Change-Id: Iaa7b81302a8d53da7dad0101f8732a0fb64f4616