The best kind of documentation is the kind you can trust is accurate. Type defs wouldn't be close to as useful if you didn't really trust them. Similarly, doctests are some of the most useful documentation because you can be sure they are accurate.
Python’s type hints are in the second category.
But now that I'm coming back to it, I think that this might be a larger category than I first envisioned, including projects whose build/release processes very reliably include the generation+validation+publication of updated docs. That doesn't imply a specific language or release automation, just a strong track record of doc-accuracy linked to releases.
In other words, if a user can validate/regenerate the docs for a project, that gets it 9/10 points. The remaining point is the squishier "the first party docs are always available and well-validated for accuracy" stuff.
Nobody does that, though. Instead they all auto-publish their OpenAPI schemas through rickety-ass, fail-soft build systems to flaky, unmonitored CDNs. Then they get mad at users who tell them when their API docs don't match their running APIs.