Thanks! And yeah we can put an empty line to break off into a new category. So essentially it's one category per paragraph. Within a paragraph, there can be sub-categories one level deep. You can also put tags inline.
I'm still trying to figure out how to allow nesting categories an arbitrary number of levels deep. But I don't want to introduce extra symbols and stuff, it'll be too much complexity too early on. I can imagine that for most cases, headings, sub-headings and inline tags are enough.
I will allow more customisation soon, such as using multiple heading identifiers. I'll add features as the need arises. I haven't used it for very long myself.