Remove XML from api doc samples

v1 API doc samples include XML:
  http://docs.openstack.org/developer/ironic/webapi/v1.html
However, the Ironic API does not support XML.

This removes the XML documentation from the generated docs.

Change-Id: I0588709190eafa52a252d19a163dc42c36f2e061
Closes-Bug: #1311268
Merge "Remove XML from api doc samples"