Helpers Docs lack of "link_class"

where is the docs repo in the GitHub?
I have found This repository , but this repository has been archived by the owner. It is now read-only.
I can make a contribution.

Helpers
link_class

This is the repository for Ghost’s official documentation, located at https://docs.ghost.org. You’ll probably just want to head over there and read them directly on the web.

Documentation is managed in Ghost now.

so can we open documentation on the Github?

Up-to-date documentation is on the Ghost sites.