doc: remove inspector experimental warning

PR-URL: #12408
Ref: #12352
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/debugger.md

@@ -200,8 +200,7 @@ flag instead of `--inspect`.
 
 ```txt
 $ node --inspect index.js
-Debugger listening on port 9229.
-Warning: This is an experimental feature and could change at any time.
+Debugger listening on 127.0.0.1:9229.
 To start debugging, open the following URL in Chrome:
     chrome-devtools://devtools/remote/serve_file/@60cd6e859b9f557d2312f5bf532f6aec5f284980/inspector.html?experiments=true&v8only=true&ws=localhost:9229/node
 ```