Optimize the docs site

[aantron]

• [ ] ~~Probably bundle resources into one HTML file, because a lot of load time is currently spent queued to issue requests for resources~~. I've used inliner for this in GraphiQL and the Playground, but it has a bug with parsing <pre><span> markup in the API docs.
• [ ] Subset fonts, especially Iosevka. Iosevka weighs 500K, half the total unoptimized site right now. There are Iosevka custom builds and separate font subset tools.
  • When subsetting Iosevka, consider switching to a dotted zero, because slashed zero is difficult to parse in 8080.
• [x] Host/bundle the remaining remote font, Tenor Sans (or drop it).
• [ ] Run highlight.js offline.