doc: explain http2 aborted event callback

Line added in the description of http2 aborted event
that it's listener does not expect any arguments.

Refs: https://github.com/nodejs/help/issues/877
PR-URL: https://github.com/nodejs/node/pull/30179


Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>