Add response examples to API documentation for following API
/v3/users/{user_id}/OS-OAUTH1/access_tokens/{access_token_id}/roles
/v3/users/{user_id}/OS-OAUTH1/access_tokens/{access_token_id}/roles/{role_id}
Change-Id: I380348d149fd917d636ef4e0e6589fffdedee2ab
Closes-Bug: #1686015