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/settings/margin/readme.mdx

@@ -0,0 +1,39 @@
+---
+title: margin
+---
+
+The `margin` setting allows you to specify a part margin (in mm).
+Each part will have this margin applied when they are laid out on the pattern.
+The default is `2 mm`.
+
+## Signature
+
+```js
+const settings = {
+  Number margin=2
+}
+```
+
+## Example
+
+```js
+import { Aaron } from "@freesewing/aaron"
+
+const pattern = new Aaron({
+  margin: 5
+})
+```
+
+## Notes
+
+The _margin_ implies that:
+- At the edge of the SVG, the margin will be `margin * 1` (2 mm by default)
+- Between parts, the margin will be `margin * 2` (4 mm by default)
+
+Setting the margin to zero (or below) will cause parts to overlap.
+
+In paperless mode, the margin will not go below 10 mm.
+That is because text is not taken into account when calculating the bounding
+box of the part.  Since dimensions are typically the outermost elements in a
+paperless part, a too narrow margin would cause the dimension text to get cut
+off.