Clarify what gerrit repositories can target neutron-specs
Clarify what gerrit repositories can target neutron-specs

It wasn't made clear by the existing documentation that we only want
neutron, neutron-fwaas, neutron-lbaas, and neutron-vpnaas repositories
to target specs at neutron-specs. This makes it 100% crystal clear.

Change-Id: I5b87faa31d71676f1674fd7370535ae6d895b43f
Signed-off-by: Kyle Mestery <9cfbda34e625c7b0454bcb19a48d07c46f9097d2@mestery.com>

chitr/neutron,mahak/neutron,openstack/neutron,glove747/liberty-neutron,MaximNevrov/neutron,cloudbase/neutron,eayunstack/neutron,dims/neutron,huntxu/neutron,noironetworks/neutron,apporc/neutron,mahak/neutron,MaximNevrov/neutron,jumpojoy/neutron,huntxu/neutron,bigswitch/neutron,openstack/neutron,sebrandon1/neutron,cloudbase/neutron,igor-toga/local-snat,klmitch/neutron,jumpojoy/neutron,yanheven/neutron,apporc/neutron,wolverineav/neutron,eayunstack/neutron,bigswitch/neutron,mahak/neutron,chitr/neutron,dims/neutron,klmitch/neutron,igor-toga/local-snat,wolverineav/neutron,sebrandon1/neutron,yanheven/neutron,noironetworks/neutron,glove747/liberty-neutron,openstack/neutron