made change to networking infro rst
made change to networking infro rst

per doc conventions plug-in needs hyphen
Closes-Bug: #1448311

Change-Id: I073a85325ebafc6122edf0aed632e28e355a5879

potsmaster/openstack-manuals,saeki-masaki/openstack-manuals,Akasurde/openstack-manuals,kairoaraujo/openstack-manuals,gongysh2004/openstack-manual,AlekhyaMallina-Vedams/openstack-manuals,potsmaster/openstack-manuals,saeki-masaki/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,gongysh2004/openstack-manual,AlekhyaMallina-Vedams/openstack-manuals,kairoaraujo/openstack-manuals,Akasurde/openstack-manuals,openstack/openstack-manuals