doc: update url doc to account for escaping

Fixes: https://github.com/nodejs/node/issues/2113
Ref: 17a379ec
PR-URL: https://github.com/nodejs/node/pull/2605


Reviewed-By: jasnell - James M Snell <jasnell@gmail.com>
Reviewed-By: cjihrig - Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: mscdex - Brian White <mscdex@mscdex.net>