Cosmetics to commands section
Introduce template for neutron appliance with ovs plugin

Due to rdo-icehouse bug [1], neutron cannot be installed by packstack
while configured with ML2 plugin, OVS as L2 agent and vlans.

Hence, the template suggests to install neutron with OVS as the plugin
instead of ML2 plugin.

[1] Bug 1095401 - Packstack failed to configure ML2 to work with OVS and VLAN