This skill should be used when the user says "document project", "generate docs", "create documentation", "write docs", "arness code document", "arn-code-document-project", "document this feature", "document this fix", or wants to generate developer documentation for a completed feature or bug fix. Reads plan artifacts, spec files, execution reports, and git diff to produce accurate documentation. Do NOT use this for general-purpose documentation — this is specifically for Arness pipeline projects.