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/stack/readme.mdx

@@ -0,0 +1,42 @@
+---
+title: Stack
+---
+
+A Stack object represents a collection of parts within a pattern.
+Stacks are used when laying out the pattern.
+
+:::note RELATED
+
+See [Stacks](/guides/designs/stacks)
+for information about how stacks are used in a pattern.
+
+:::
+
+## Signature
+
+```js
+Stack new Stack(String name)
+```
+
+The stack constructor takes a single argument, a String containing the name
+of the stack.
+
+## Properties
+
+Stack objects come with the following properties:
+
+- `attributes` : An [Attributes](/reference/api/attributes) instance holding the stack's attributes
+- `parts` : A set of parts in the stack
+- `name` : The name of the stack
+- `topleft` : A [Point](/reference/api/point) that is the top left of the stack's bounding box
+- `bottomRight` : A [Point](/reference/api/point) that is the bottom right of the stack's bounding box
+- `width` : The width of the stack in mm
+- `height` : The height of the stack in mm
+- `anchor` : A [Point](/reference/api/point) that is used as the anchor to align parts in the stack
+
+
+## Methods
+
+A Stack object exposes the following methods:
+
+<ReadMore />