http2: graduate from experimental

Backport-PR-URL: #22850
PR-URL: #22466
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Yuta Hiroto <hello@hiroppy.me>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

doc/api/http2.md

@@ -1,8 +1,14 @@
 # HTTP/2
-
+<!-- YAML
+added: v8.4.0
+changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/22466
+    description: HTTP/2 is now Stable. Previously, it had been Experimental.
+-->
 <!--introduced_in=v8.4.0-->
 
-> Stability: 1 - Experimental
+> Stability: 2 - Stable
 
 The `http2` module provides an implementation of the [HTTP/2][] protocol. It
 can be accessed using:

lib/http2.js

@@ -1,11 +1,5 @@
 'use strict';
 
-process.emitWarning(
-  'The http2 module is an experimental API.',
-  'ExperimentalWarning', undefined,
-  'See https://github.com/nodejs/http2'
-);
-
 const {
   constants,
   getDefaultSettings,