I think it's the standard https://readthedocs.org/ https://readthedocs.org/ standard. It's definitely not custom. I've seen many projects with it. Edit: Seems

I think it's the standard https://readthedocs.org/ https://readthedocs.org/ standard. It's definitely not custom. I've seen many projects with it. Edit: Seems to be linked to the doc tool called Sphinx.