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/attributes/getasarray/readme.mdx

@@ -0,0 +1,23 @@
+---
+title: Attributes.getAsArray()
+---
+
+The `Attributes.getAsArray()` method will return an array with the value of
+attribute stored under `key`, or `false` if it's not set.
+
+## Signature
+
+```js
+array attributes.getAsArray(string key)
+```
+
+## Example
+
+```js
+const attr = new Attributes()
+  .add('class', 'classA')
+  .add('class', 'classB')
+
+const class = attr.getAsArray('class')
+// class now holds: [ "classA", "classB" ]
+```