[networking] Correct the target release
[networking] Correct the target release

The master branch of the networking guide documents
the Newton release.

Change-Id: If98b07139893be8d4d7b7e0208eeb56bad41f4c5

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