Lack of documentation for Swift/Cinder measurements

[Cyril Roelandt]

I had a hard time finding instructions on how to get Cinder and Swift (more specifically, storage.objects.{incoming,outgoing}.bytes) working with Ceilometer.

Possible fix: in http://docs.openstack.org/developer/ceilometer/measurements.html , add complementary information and links to http://docs.openstack.org/developer/ceilometer/install/manual.html when needed.