Comment 2 for bug 1660687

Looks like [1] needs to be updated to describe the hybrid driver system.

[2] Definitely needs updating to mention the option.

[3] Made changes to the linuxbridge docs, despite this change only applying to OVS, so that's a bit confusing.

The description in [4] could certainly offer more detail.

[1] http://docs.openstack.org/draft/networking-guide/config-ovsfwdriver.html
[2] http://docs.openstack.org/newton/config-reference/networking/networking_options_reference.html#open-vswitch-agent-configuration-options
[3] https://review.openstack.org/#/c/377830
[4] http://docs.openstack.org/newton/config-reference/networking/networking_options_reference.html#security-groups