Cross-links

Write `term` anywhere in a body. It auto-links to the glossary.

In any field rendered through `md()` — `body`, `gesture`, `eli5` — wrap a term in double square brackets and it becomes a link to that entry in the glossary. The match is case-insensitive against the glossary keys. The glossary itself is a single object in `src/lib/glossary.js`. Cross-references between glossary entries are supported via a `see` array. There is no separate authoring step; you just write `gesture` and it links.