stackrc: update code comment now that Neutron is enabled by default
stackrc: update code comment now that Neutron is enabled by default

No need to explain how to enable Neutron now that it's enabled by
default. Keep but reformat the 'how to enable swift' part though.

Change-Id: I3f9b7796fad10abf1039e4c68eb2cd5ef6cdbc99

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