I like the practice of keeping the documentation in sync with the code by marking relevant code lines inside special quotes. Moreover, the CI ensures that if the marked line gets changed so the docs also have to be reviewed.

That it is super fun to use and the use case is extremely relevant. I especially appreciate the "Playlist" feature that allows me to dynamically document the codebase spread across multiple services and repositories.

Swimm helps me document processes that are cross files, I created one document with all the code snippets that I need and added explanations. And if the code has changed I could see that my document needs an update.