Upgrades the docs to `@vercel/geistdocs@1.16.0`.
- Bump `@vercel/geistdocs` 1.15.5 → 1.16.0
- Drop the removed `config` prop from `<Footer />` (1.16.0 replaces the
footer with the Vercel product directory and no longer accepts props)
- Load Geist Sans from the `geist` npm package so the new `ss11`
stylistic set (alternate "I") renders — Google Fonts strips it