chore: Port FreeSewing.dev to docusaurus

The replaces the NextJS site powering FreeSewing.dev with a Docusaurus
setup. It's part of my efforts to simplify FreeSewing's setup so we can
focus on our core value proposition.

sites/dev/docs/reference/api/utils/units/readme.mdx

@@ -0,0 +1,19 @@
+---
+title: utils.units()
+---
+
+The `utils.units()` function converts the units `value` you pass it into a
+formatted string for the `format` you pass it.
+
+## Signature
+
+```js
+string utils.units(float value, string format = 'metric')
+```
+
+Format must be either `imperial` or `metric` (the default).
+
+## Notes
+
+A [part's `draft()` function](/reference/api/part/draft) receives a context-aware
+`unit()` function that will call this function and pass it the units requested by the user.