[
  {
    "body": {
      "event": "BackupStarted"
    },
    "age": 239,
    "href": "/v2/queues/demoqueue/messages/51db6f78c508f17ddc924357?claim_id=51db7067821e727dc24df754",
    "ttl": 300
  }
]
{
    "messages": [
        {
            "body": {
                "event": "BackupStarted"
            },
            "age": 239,
            "href": "/v2/queues/demoqueue/messages/51db6f78c508f17ddc924357?claim_id=51db7067821e727dc24df754",
            "ttl": 300
        }
    ]
}

Fix a minor error in API reference
Fix a minor error in API reference

Based on test result, response body of claim messages API
includes a top level key "messages" whose vlaue is a list of
messages being successfully claimed. This patch revises
corresponding sample in API reference.

Change-Id: I72b7b7a59e9c54c398448e474d2d13f77454e29c
