doc: mention ovs controller tcp port (seems required by Ubuntu >= 15.10)
doc: mention ovs controller tcp port (seems required by Ubuntu >= 15.10)

AkihiroSuda/earthquake,osrg/namazu,osrg/earthquake,osrg/namazu,osrg/earthquake,AkihiroSuda/earthquake,AkihiroSuda/earthquake,AkihiroSuda/earthquake,AkihiroSuda/earthquake,osrg/namazu,AkihiroSuda/earthquake,AkihiroSuda/earthquake,osrg/earthquake,osrg/namazu,osrg/earthquake,osrg/earthquake,osrg/namazu,osrg/earthquake,AkihiroSuda/earthquake,osrg/namazu,osrg/earthquake,osrg/namazu