Write Documentation

Ensures that the documentation of the repository is complete, correct and up to date.

The measure of documentation quality is not its length. It is whether a competent person who does not know this repository can, using only the documentation: understand what the repository is for, get it running, change something safely, and contribute in the expected way.

Two rules override everything else:

1. Wrong documentation is worse than none. A README command that no longer works costs a reader more time than an empty README. Verifying existing documentation therefore comes before writing new documentation.
2. Document what cannot be read off the code: purpose, contracts, constraints, and the why behind non-obvious decisions. Never paraphrase the implementation — that kind of text is wrong after the first refactoring and nobody notices.

Completion criterion