Edits on section_nova-network.xml
Edits on section_nova-network.xml

As suggested by Diane in
https://review.openstack.org/#/c/55950/1/doc/install-guide/section_nova-network.xml

Change-Id: Id5dd614d638fd9bd1bb620423842f4f15fe0b5d5
backport: havana

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