docs: link an operator guide for running a witness (#54)

The card offered a mirroring guide and nothing for the other half of its
own heading. Action State has published an operator guide for running a
witness: endpoints and schema, deploy, backup and restore with a
cryptographic restore check, key rotation, offline receipt verification
without contacting the witness, and registering one checkpoint with more
than one witness. It marks hardware key custody, continuity checking and
refusing the write on equivocation as planned rather than shipped.

Read before linking: it describes running a witness under your own domain
and your own key, with their code as optional tooling rather than a
dependency, which is the only version worth linking from a page that says
single-operator dependency is a weakness.


Claude-Session: https://claude.ai/code/session_01RMuXK1es7dsRsPtvC5Tkpd

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: imran-siddique

registry/index.html

@@ -238,7 +238,7 @@ <h2>What a registry entry is, and what it is not</h2>
   <h2>Three ways in</h2>
   <div class="grid-3">
     <article class="card"><h3>Register as a producer</h3><p>Publish anchors for your own signed trust records under your own key. The conventions, naming, and submission path are documented in the repository.</p><a href="https://github.com/agentrust-io/trace-registry/blob/main/CONTRIBUTING.md">Read the contributor guide →</a></article>
-    <article class="card"><h3>Run a mirror or a witness</h3><p>Single-operator dependency is a weakness we name rather than hide. Independent mirrors and independent witnesses can reduce it when observers retain and compare evidence. Neither is a blanket guarantee against split views.</p><a href="https://github.com/agentrust-io/trace-registry/blob/main/MIRRORS.md">Mirroring guide →</a></article>
+    <article class="card"><h3>Run a mirror or a witness</h3><p>Single-operator dependency is a weakness we name rather than hide. Independent mirrors and independent witnesses can reduce it when observers retain and compare evidence. Neither is a blanket guarantee against split views.</p><a href="https://github.com/agentrust-io/trace-registry/blob/main/MIRRORS.md">Mirroring guide &rarr;</a> <a href="https://github.com/action-state-group/capsule-anchor/blob/main/OPERATOR_GUIDE.md">Witness guide &rarr;</a></article>
     <article class="card"><h3>Attack the claims</h3><p>The most useful contribution is a demonstration that something on this page overstates what the code actually does. Open an issue in public.</p><a href="https://github.com/agentrust-io/trace-registry/issues">Open an issue →</a></article>
   </div>
 </section>