Explicitly state what is returned on create and update

Change text in 11.4.2 to (new text in green) Upon successful completion the service MUST respond with either 201 Created and a representation of the created entity , or 204 No Content if the request included a Prefer header with a value of return=minimal . Change text in 11.4.3 to (new text in green) Upon successful completion the service responds with either 200 OK and a representation of the updated entity, or 204 No Content .