[networking] RFC 5737: misc-libvirt
[networking] RFC 5737: misc-libvirt

Replaces non-compliant subnets in:

misc-libvirt.rst

Change-Id: Ib02ada4681849f036d61cb0e3f415b8353f8c1ff
Partial-Bug: #1656378

openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals