doc: improve docs for Http2Session:frameError

Improve documentation regarding the callback parameters for the
frameError event for instances of Http2Session, making it inline with
the currently accepted structure, like 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/20236


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