docs(webhook): adding GitLab doc to webhooks
docs(webhook): adding GitLab doc to webhooks

rtfd/readthedocs.org,pombredanne/readthedocs.org,davidfischer/readthedocs.org,safwanrahman/readthedocs.org,davidfischer/readthedocs.org,davidfischer/readthedocs.org,rtfd/readthedocs.org,davidfischer/readthedocs.org,safwanrahman/readthedocs.org,pombredanne/readthedocs.org,rtfd/readthedocs.org,pombredanne/readthedocs.org,rtfd/readthedocs.org,safwanrahman/readthedocs.org,safwanrahman/readthedocs.org