doc: close event does not take arguments

Explicitly added in the docs that the close event does not expect
any arguments when invoked.

Fixes: #20018

PR-URL: #20031
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/http2.md

@@ -128,7 +128,8 @@ solely on the API of the `Http2Session`.
 added: v8.4.0
 -->
 
-The `'close'` event is emitted once the `Http2Session` has been destroyed.
+The `'close'` event is emitted once the `Http2Session` has been destroyed. Its
+listener does not expect any arguments.
 
 #### Event: 'connect'
 <!-- YAML