Comment 4 for bug 1612786

Pulled from review comments (good points, thanks bnemec!)

"... this constraint needs to be added to our nic-configs since those are where the bond options get applied to a system. Actually, I still think we need a proper external validation for this since it involves templates that users will be editing, and thus may have existing versions without this constraint that will be carried forward into this release, but I'm good with this as a partial fix until the validations framework is fully integrated.
Note that we also need to fix the examples in http://docs.openstack.org/developer/tripleo-docs/advanced_deployment/network_isolation.html to include the constraint, besides the sample nic-configs we ship in t-h-t."