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/readme.mdx

@@ -0,0 +1,22 @@
+---
+title: Defs
+---
+
+The `Defs` object in FreeSewing's core library represents an SVG document's
+[`defs` element](https://developer.mozilla.org/en-US/docs/Web/SVG/Element/defs).
+It is not directly exposed, but it is available as the `defs` attribute
+of an [Svg object](/reference/api/svg/defs).
+
+While the properties and methods exposed by this object are typically only used internally,
+they are documented here to facilitate development of plugins.
+
+## Properties
+
+A Defs object comes with the following property:
+
+- `list` : Holds the internal object in which entries of the `defs` element are stored
+
+## Defs methods
+
+<ReadMore />
+