docs: say where the tests are and how to reproduce this tree

[open-coder-ai]

Why

A Copilot review on the GitHub marketplace submission flagged that our entries "expose externally implemented security enforcement without repository-local integration tests."

The observation is correct, and it will be raised by every marketplace we submit to — so this closes it in the repository rather than in one comment thread.

The gap was documentation, not testing

The policies are tested. Every policy in the catalog ships base/*/evals/suite.yaml, and publish.yml runs chock check and chock check --only evals as a gate before anything is packaged — a policy whose evals fail cannot reach this repository.

None of that was discoverable from here. The word "eval" appeared zero times in this README and in PLUGINS.md. A reviewer following the listing's repository: link landed on a page asserting trustworthiness with no way to check it.

What this adds to the Trust section

• Where the tests are, and why they're there — the catalog holds policy source; this repo is compiled output. Tests belong with source.
• A runnable reproduction — clone this tree, the catalog and the framework at the release it was published from, rebuild, diff. Two silent git commands mean byte-identical.
• An honest caveat — this README is the one file publish.yml never writes, so it alone sits outside the generated-only guarantee. A page about what may be trusted should say where it stands itself.
• Pinning guidance — tag and full SHA. A tag alone is a movable reference; the SHA is what holds reviewed bytes still.

The recipe was run, not derived

I executed it against this repository before writing it down — a verification procedure nobody has run is exactly the unearned claim this section exists to avoid.

chock-claude-plugins     CLEAN
chock-cursor-plugins     CLEAN
chock-codex-plugins      CLEAN
chock-copilot-plugins    CLEAN

All four reproduce byte-identically from catalog ed2930e + chock v0.7.0.

Checks

• No generated content touched — README only, so generated-only is unaffected.
• Bullet style matches this repo's existing Trust section.

Noted while verifying — not fixed here

generated-only.yml checks out open-coder-ai/chock with no ref:, so it verifies against a moving main, while publish.yml builds from a pinned framework_ref. They agree today only because chock's two commits past v0.7.0 are CI-only and don't touch the emitter. The next chock merge that changes emitter output turns this repo's verify red on an untouched tree. Worth its own change; deliberately not bundled with a docs PR.