doc: get rid of unnecessary eslint-skip comments

PR-URL: https://github.com/nodejs/node/pull/50829
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ethan Arrowood <ethan@arrowood.dev>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>

doc/api/errors.md

@@ -2940,9 +2940,7 @@ signal (such as [`subprocess.kill()`][]).
 [self-reference a package using its name][] and [define a custom subpath][] in
 the [`"exports"`][] field of the [`package.json`][] file.
 
-<!-- eslint-skip -->
-
-```js
+```mjs
 import './'; // unsupported
 import './index.js'; // supported
 import 'package-name'; // supported