Streamline html and md page build

[robinmetral]

Currently, html pages are simply fed to mustache. md pages are first fed to unified, which runs them through a series of plugins, and then the output html is fed to mustache.

This can create weird behaviors. For example, if a page is written in md, then its heading will get automatic ids for in-document references. If the same page is in html, they won't.

Potential solutions:

• do nothing, this is fine
• run html pages through unified in a slightly different pipeline (rehype-parse 👉 rehype plugins 👉 rehype-stringify). The remark plugins wouldn't take effect (and I don't think they should, if something can be done on either the mdast or the hast it should be done on the hast) but the rehype plugins would.
• decide that ALL pages should be markdown. html should be only for templating.
  • what about templates that have separate content "slots"?