doc: add hints to http.request() options

PR-URL: https://github.com/nodejs/node/pull/37745


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>