You need to feed something into the github node in a variable named path to start the recursion of directories from there. The pinned data in the previous example has { “path”: “/” } to start things off.
You could also do that with a Set Edit Data node, but ultimately you need something to set it up for your first call to github. If you are familiar with how a recursive function works, this is very similar. The items passed back to the github node through the loop are only the directories, so then you would be using that path and finding .md files and other subdirectories within each of those.