Yes, sorry—I should have been abundantly clear that I was responding only to the "You can figure it out yourself from the header file, you don't need docs" point. If it's an unfinished or hobby project, great! Those are cool, and I don't mean to discourage them / place high bars on them existing in public, and I am super sorry for not being clear about that.

Hobby or personal-interest projects with an expectation of no real use don't need externally-facing documentation because they have no externally-facing APIs at all, not because their APIs are obvious.