docs: rebase onto current main -- add the page to the nav and repoint the operator-runbook link

- mkdocs.yml: list 'Working with the agent' in the nav (a page not in the
  nav is hard to find).
- working-with-the-agent.md: the operator token runbook moved out of the
  published site into the git-only co-op/ops-docs, so the relative link
  (operator-token-runbook.md) would 404; point it at the runbook's new home
  in ops-docs, as infrastructure.md already does. Wording unchanged.

mkdocs.yml

@@ -74,6 +74,7 @@ nav:
   - Energy & carbon: energy.md
   - Infrastructure: infrastructure.md
   - Background: background.md
+  - Working with the agent: working-with-the-agent.md
   - Governance:
       - Charter: charter.md
       - Code of conduct: code-of-conduct.md