doc: correct callback parameter type for createPushResponse()

Refs: #22322 (comment)

PR-URL: #36631
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: Trott

doc/api/http2.md

@@ -3642,7 +3642,8 @@ added: v8.4.0
   has been rejected, or the state of `Http2ServerRequest` is closed prior to
   calling the `http2stream.pushStream()` method
   * `err` {Error}
-  * `stream` {ServerHttp2Stream} The newly-created `ServerHttp2Stream` object
+  * `res` {http2.Http2ServerResponse} The newly-created `Http2ServerResponse`
+    object
 
 Call [`http2stream.pushStream()`][] with the given headers, and wrap the
 given [`Http2Stream`][] on a newly created `Http2ServerResponse` as the callback