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/hooks/postrender/readme.mdx

@@ -0,0 +1,19 @@
+---
+title: postRender
+---
+
+The `postRender` lifecycle hook is triggered after the SVG is rendered.
+It will only fire when `Pattern.render()` is called.
+
+## Signature
+
+```js
+null hook(Svg svg)
+```
+
+## Notes
+
+The `postRender` hook is rarely used, but it's there if you need it.
+
+Like the `preRender` hook, it receives [the SVG object](/reference/api/svg) as its first
+parameter.