Make clear this is the documentation, not the co-op homepage:
- site_name -> 'Inference Cooperative docs' (drives the <title> and the
header brand on every page)
- homepage h1 -> 'Inference Cooperative docs'
- footer gains a 'Co-op homepage' link to https://inference.coop/, added
in the existing copyright.html override alongside the Gitea source link
- README: render the Key links as real Markdown links (mailto: for the
contact address); drop the 'lives in a public git repository' note now
that the footer carries the source link.
- mkdocs.yml: add a theme override (custom_dir: overrides) that puts a
'Documentation source' link in the footer of every page.
- Move the operator runbook, maintenance notes and incident write-up out
of the published site into the git-only co-op/ops-docs repository;
remove them from the nav and repoint cross-references at Gitea.