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/snippets/buttonhole-start/readme.mdx

@@ -0,0 +1,42 @@
+---
+title: buttonhole-start
+---
+
+The `buttonhole-start` snippet is used to mark buttonhole placement.
+This particular snippet places the buttonhole's start on its
+anchor point.
+
+It is provided by [plugin-annotations](/reference/plugins/annotations/), which is
+part of [core-plugins](/reference/plugins/core) (so it is available by default).
+
+## Example
+
+<Example caption="An example of the buttonhole-start snippet">
+```js
+({ Point, Path, paths, Snippet, snippets, part }) => {
+
+  snippets.demo = new Snippet('buttonhole-start', new Point(0,0))
+
+  // Show alignment
+  paths.anchor = new Path()
+    .move(new Point(-5, 0))
+    .line(new Point(5, 0))
+    .addClass('dotted note stroke-sm')
+
+  // Prevent clipping
+  paths.diag = new Path()
+    .move(new Point(-50,-4))
+    .move(new Point(50,4))
+
+  return part
+}
+```
+</Example>
+
+## Notes
+
+We provide three buttonhole snippets with a different alignment:
+
+- [buttonhole](/reference/snippets/buttonhole/): Anchor point is the middle of the buttonhole
+- [buttonhole-start](/reference/snippets/buttonhole-start/): Anchor point is the start of the buttonhole
+- [buttonhole-end](/reference/snippets/buttonhole-end/): Anchor point is the end of the buttonhole