doc,http2: add parameters for Http2Session:connect event

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

Refs: nodejs/help#877 (comment)

Backport-PR-URL: #22850
PR-URL: #20193
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>

doc/api/http2.md

@@ -136,6 +136,9 @@ listener does not expect any arguments.
 added: v8.4.0
 -->
 
+* `session` {Http2Session}
+* `socket` {net.Socket}
+
 The `'connect'` event is emitted once the `Http2Session` has been successfully
 connected to the remote peer and communication may begin.