devref doc config option separation
devref doc config option separation

Document separation of configuration options between services and agents.

Configurations used in devstack and deployment documentation should also be
updated since they are referenced as examples.

Partial-Bug: #1557119
Change-Id: Ia4b2a542cded6cc56c1b3eaa9e9b9e0abff31707

eayunstack/neutron,igor-toga/local-snat,cloudbase/neutron,openstack/neutron,huntxu/neutron,sebrandon1/neutron,eayunstack/neutron,openstack/neutron,noironetworks/neutron,igor-toga/local-snat,openstack/neutron,cloudbase/neutron,sebrandon1/neutron,mahak/neutron,mahak/neutron,huntxu/neutron,noironetworks/neutron,mahak/neutron