Program will evolve and documentation will go out of date before it's gonna be read a single time. So a variant of 1)

Personally I don't write documentation because I don't read documentation. It's too often pure garbage, less reliable than 2023 LLM output so I just skip it and go to the source code.

I would read documentation written for AI because I know for a fact that it describes the thing accurately enough if the system works. Human addressed documentation almost always has no verification.