doc: fix nits in esm.md

* ```mjs -> ```js as our linting of doc code fragments
  does not recognize this tag, IIRC.

* Add semicolons to a code fragment.

* Fix ASCII sorting in bottom references.

PR-URL: https://github.com/nodejs/node/pull/29242


Reviewed-By: Guy Bedford <guybedford@gmail.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>