doc: fix typo in api doc of url.format(urlObject)

PR-URL: https://github.com/nodejs/node/pull/17295
Fixes: https://github.com/nodejs/node/issues/17294


Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>