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/snippet/attr/readme.mdx

@@ -0,0 +1,47 @@
+---
+title: Snippet.attr()
+---
+
+The `Snippet.attr()` method can be used to add attributes to the Snippet
+object.  It calls `this.attributes.add()` under the hood, and returns the
+Snippet object.
+
+If the third parameter is set to `true` it will call `this.attributes.set()`
+instead, thereby overwriting the value of the attribute.
+
+## Signature
+
+```js
+Snippet snippet.attr(
+  string name, 
+  mixed value, 
+  bool overwrite = false
+)
+```
+
+:::tipThis method is chainable as it returns the `Snippet` object:::
+
+## Example
+
+<Example caption="An example of the Snippet.attr() method">
+```js
+({ Point, points, Path, paths, Snippet, snippets, part }) => {
+
+  snippets.logo = new Snippet('logo', new Point(0,0))
+    .attr("data-scale", 0.75)
+    .attr("data-rotate", 180)
+
+  // Prevent clipping
+  paths.diag = new Path()
+    .move(new Point(-25,-10))
+    .move(new Point(25,35))
+
+  return part
+}
+```
+</Example>
+
+:::note RELATED
+See [Using Attributes](/howtos/code/attributes)
+for information about what Attributes can be used with Snippets.
+:::