Added doc support for quotas API ext.

Modified:  api-ref/src/wadls/compute-api/src/ext/os-quota-sets.wadl
This change mostly adds xml samples to the API, but also corrects the req/resp samples for 'update quotas'.
Fixes: bug 1086000

Change-Id: I54fa4e076fa3d610bfd707ab1ccb904feca8f99a
Merge "Added doc support for quotas API ext."