Add more commit msg tips to 'effective neutron'
Add more commit msg tips to 'effective neutron'

This adds a few more tips to the commit message guidelines in
the effective neutron devref.

Change-Id: I31ae7cb4303ff36aa9359d3fe284dde9a7ed8757

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