What software is used to create the Grav Wiki?

I have seen this wiki layout on many websites and im curious to know what software it is.
https://learn.getgrav.org/

It is a variant of the Grav skeleton RTFM (https://getgrav.org/downloads/skeletons) and theme Learn2 (https://getgrav.org/downloads/themes). Both are very similar to https://readthedocs.org/.