Adds the tracedocs skill (tracedocs/SKILL.md) and a README entry under Development & Code Tools.

tracedocs turns any codebase into an evidence-grounded Markdown documentation package plus a machine-readable index.json for AI agents. Every operational/deployment claim cites its source file and carries a confidence label (Verified / Inferred / Unknown / Needs confirmation); it never invents deployment steps and documents gaps instead.

• Real, tested use case: a complete validated sample is committed at examples/study-docs/ in the source repo
• Portable: plain SKILL.md + references; works in Claude Code, Codex, and other agents; also packaged as a Claude Code plugin
• Source: https://github.com/wxggzz/tracedocs (MIT)

Followed the SKILL.md template in CONTRIBUTING (When to Use / What This Skill Does / How to Use / Example / Tips / Common Use Cases).