Be a bit more explicit about the plugin generation
Be a bit more explicit about the plugin generation

Make the warning in the auto-generated file stand-out a bit more, so
people don't waste time trying to add entries that appear
automatically.

Change-Id: Icf4290e1fad21ce72af54c178bafcce0b287cdf6

openstack-dev/devstack,dtroyer/devstack,nawawi/openstack,Mahito/devstack,bswartz/devstack,nawawi/openstack,bswartz/devstack,dtroyer/devstack,richliu/devstack,bigswitch/devstack,richliu/devstack,group-policy/devstack,noironetworks/devstack,noironetworks/devstack,openstack-dev/devstack,Mahito/devstack,group-policy/devstack,bigswitch/devstack