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/plugins/core/readme.mdx

@@ -0,0 +1,39 @@
+---
+title: core-plugins
+---
+
+Published as [@freesewing/core-plugins][1], our core plugins bundles the most
+commonly used FreeSewing plugins in one bundle that is loaded by the core
+library by default. 
+
+Specifically, loading this plugin will have the same effect as loading these
+plugins individually:
+
+
+- [plugin-annotations](/reference/plugins/annotations) : A variety of snippets, macros, and store methods for annotating patterns
+- [plugin-measurements](/reference/plugins/measurements) : Make extra, calculated measurements available to your patterns
+- [plugin-mirror](/reference/plugins/mirror) : Mirror points and paths in your patterns
+- [plugin-round](/reference/plugins/round) : Create rounded corners in your patterns
+- [plugin-sprinkle](/reference/plugins/sprinkle) : Add multiple snippets to your patterns
+- [plugin-binpack](https://github.com/freesewing/freesewing/tree/develop/plugins/plugin-bin-pack) : The default bin packing algorithm used to handle auto-generated layouts in core
+
+## Installation
+
+```bash
+npm install @freesewing/core-plugins
+```
+
+## Usage
+
+The core plugins are loaded by default so there is nothing to be done to use them.
+
+If you do not want to load the core plugins, pass `noCorePlugins: true` to your Design constructor:
+
+```mjs
+const design = new Design({ 
+  parts: myParts, 
+  noCorePlugins: true 
+})
+```
+
+[1]: https://www.npmjs.com/package/@freesewing/core-plugins