Can't get dirtree to show up

[pinpox]

Hey, this might be more of a question than an issue but I couldn't figure it out form the documentation:

I'm trying to get a the dirtree plugin to work, if I understand correctly it should tag (sub-)folders according to their name.

Here is my simple example: https://github.com/pinpox/zettelkasten

It containes two subfolders (categories) with 2 posts each, how do I show that correctly in the index.md? It looks like this currently (no posts shown):

How would I make the main index.md page show some predefined header + the cathegories with a list of all files in them (or maybe the last 10 of them)?

[srid]

[[z:zettels?tag=Motorcycles]]

I believe this should instead be:

[[z:zettels?tag=root/Motorcycles]]

The dirtree plugin prefixes every hierarchical tag it generates with root/ (so as to avoid conflict with user's tags).