Update README to point at official Managed VMs web site.
Update README to point at official Managed VMs web site.

Change-Id: Idb3de4751ee3ab4777e5d45d7896f837fc4efa08

flowlo/appengine,mzimmerman/appengine,fuchsia-mirror/third_party-github.com-golang-appengine,fuchsia-mirror/third_party-github.com-golang-appengine,skyeunknown084/appengine,skyeunknown084/appengine,flowlo/appengine,flowlo/appengine,mzimmerman/appengine,skyeunknown084/appengine,golang/appengine,mzimmerman/appengine,golang/appengine