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/defs/set/readme.mdx

@@ -0,0 +1,17 @@
+---
+title: Defs.set()
+---
+
+Sets the defs entry stored under _name_ to _value_.
+
+## Signature
+
+```js
+Defs defs.set(
+  String name,
+  String value
+)
+```
+
+This object is chainable as it returns the `Defs` object.
+