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/pattern/readme.mdx

@@ -0,0 +1,85 @@
+---
+title: Pattern
+---
+
+The `Pattern` object in FreeSewing's core library holds all data and logic of a pattern.
+It is the parametric blueprint that when instantiated with a user's settings
+can draft a bespoke sewing pattern.
+
+## Creating a Pattern
+
+A Pattern in FreeSewing is an instantiated Design:
+
+```js
+import { Florence } from "@freesewing/florence"
+
+const pattern = new Florence()
+```
+
+You probably want to create a pattern using your own [settings](/reference/settings):
+
+```js
+import { Florence } from "@freesewing/florence"
+
+const pattern = new Florence({
+  paperless: true,
+  measurements: {
+    head: 390,
+  }
+})
+```
+
+## Multisets in FreeSewing
+
+You can pass the Pattern constructor an array of multiple settings objects:
+
+```js
+import { Florence } from "@freesewing/florence"
+
+const pattern = new Florence([
+  {
+    measurements: {
+      head: 390,
+    }
+  },
+  {
+    measurements: {
+      head: 420,
+    }
+  },
+])
+```
+
+We refer to these *multiple sets of settings* as **multisets**.
+It is what powers FreeSewing's [sampling capabilities](/reference/api/pattern/sample) but
+it also allows you to draft some pattern parts with one set of measurements, and other parts
+with another set. For example if you have an asymmetric model to fit.
+
+:::note
+
+##### Core always keeps a set of settings
+
+Multisets is an advanced feature of FreeSewing, and for the most part you can forget about it
+until the day you want to use it.
+
+However, it's good to keep in mind that under the hood, FreeSewing will always use a set of settings.
+It just so happens that in most cases, there will be only one settings object in the set.
+
+:::
+
+## Pattern attributes
+
+- `Pattern.activePart`: Holds the id of the active part (while drafting)
+- `Pattern.activeSet`: Holds the id of the active set (while drafting)
+- `Pattern.config`: Holds the resolved pattern's configuration
+- `Pattern.designConfig`: Holds the design's configuration before resolution
+- `Pattern.parts`: Holds the parts used in the pattern
+- `Pattern.plugins`: Holds the plugins used in the pattern
+- `Pattern.settings`: Holds the settings used for the pattern
+- `Pattern.stacks`: Holds the stacks used in the pattern
+- `Pattern.store`: Holds the pattern-wide Store
+- `Pattern.setStores`: Holds an array of stores, one for each set of settings.
+
+## Pattern methods
+
+<ReadMore />