The built-in node help menu is now available to everyone. Just update your ComfyUI to the latest version and make sure the frontend is at least v1.22.2.

The node docs are still not perfect. If you find any errors or want to help improve them, you can submit a PR to this repo: https://github.com/Comfy-Org/embedded-docs

@ComfyUIWiki is working on it as well.