doc: update message.url example in http.IncomingMessage
Update message.url example to use The WHATWG URL API. This is because the old example suggests using deprecated url API.
Fixes: https://github.com/nodejs/node/issues/30048 Refs: https://nodejs.org/dist/latest-v12.x/docs/api/http.html#http_message_url
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
documentation is changed or added -
commit message follows commit guidelines