doc: add parameters for settings events

Add parameters for the callback for the Http2Session:localSettings event
and Http2Session:remoteSettings event inline with the pattern in the
rest of the documentation.

Refs: https://github.com/nodejs/help/issues/877#issuecomment-381253464

Backport-PR-URL: https://github.com/nodejs/node/pull/22850
PR-URL: https://github.com/nodejs/node/pull/20371


Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>