This patch updates the api-ref to indicate that ``Range`` shall be
accepted in the request header and upon a successful serving of the
partial image data, the response headers would include ``Content-Range``.
Change-Id: I99ecc345793c7f3045400e57711f01cae2181f6f
Depends-On: b7ebc792c32995751744be3f36cbc9a0c1eead2a
9033cbe149