Yes, there are even documentations about documentation which is itself a bit of a paradox when you think about it. But there are many documentation sources out today for just that purpose.
In fact Obsidian itself is a fantastic documentation source. It serves to explain and give tutorials for me. Just stick with one though.
The themes themselves or the front matter for documentation is certainly worth mentioning. Of course you can also just skip that whole process and go directly into simple html design. But aesthetics do matter at the end of the day. Here are notable themes.
- This [Re-learn Hugo Theme](https://mcshelby.github.io/hugo-theme-relearn/basics/index.html) for docs