Document static server requirements

[Fil]

We should list expectations on how to serve the built site.

For example, the side bar links to URL /contributing but the server must respond with the contents of the contributing.html file; if you use python3 -m http.server or npx live-server to serve the dist folder, this results in a 404 when using the navigation bar.

Would it make sense to have a yarn serve command that serves the built site (with http-server or npx http-server, or with a custom ./src/serve.ts)?

[Fil]

For example when pushing a site to vercel, you need to add a vercel.json file with the {cleanUrls: true} option.

[mbostock]

I feel like this should be closed in favor of #92.

[mbostock]

Closing in favor of #92.