Docs that stay true.
Documentation dies when it lives far from the work. Keep it close to the code, review it like code, and use it for real.
Docs as code
In The Repo
Markdown next to the code, changed in the same pull request.
Decision records
Why, Not Just What
Short ADRs recording why a choice was made (Michael Nygard).
Runbooks
Tested In Drills
Operational steps, proven by actually following them.
README first
Run It In Ten Minutes
What it does, how to run it, who owns it, how to deploy.
Source: Cognitect: Michael Nygard, 'Documenting Architecture Decisions' ↗
Close to the code. Reviewed like code. Used for real.