1. Documentation driven development - write the explanatory docs before the feature or project in markdown.

2. hitchstory for executable tests that generate up-to-date how to docs with screenshots or whatever. I tend to write all how to docs as tests.

3. OpenAPI for API docs. Sometimes I have scripts that generates lists of enums too, etc.

4. Some sort of script that ties all of the above together and generates a documentation artefact on each build.