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/part/config/plugins/readme.mdx

@@ -0,0 +1,68 @@
+---
+title: Part plugins
+---
+
+The `plugins` property on the part configuration object 
+list the plugins that are used in/required by the part:
+
+```js
+import { pluginBundle } from '@freesewing/plugin-bundle'
+import { pluginBust } from '@freesewing/plugin-bust'
+
+const part = {
+  name: 'example.front',
+  plugins: [ pluginBundle, pluginBust ],
+  draft: ({ part }) => part
+}
+```
+:::tip
+
+You should only list the plugins that are required by the part itself,
+not those required by its dependencies
+
+:::
+
+## Passing data to a plugin
+
+Some plugins require you to pass data to the plugin.
+For these, pass an `[plugin, data]` array:
+
+```js
+import { pluginBundle } from '@freesewing/plugin-bundle'
+import { myDataPlugin } from 'myDataPlugin'
+
+const myData = {
+  some: 'data'
+}
+
+const part = {
+  name: 'example.front',
+  plugins: [ pluginBundle, [ myDataPlugin, data ] ],
+  draft: ({ part }) => part
+}
+```
+
+## Conditional plugins
+
+A conditional plugin is loaded only when a condition is met.
+The plugin and condition should be provided as an `Object`
+with the following structure:
+
+```js
+import myPlugin from './my-plugin.mjs'
+
+const myConditionalPlugin = {
+  myPlugin,
+  condition,
+}
+```
+
+Where `myPlugin` is the plugin itself, and `condition` is a method
+that returns `true` if the plugin should be loaded.
+
+:::note RELATED
+
+Refer to [the plugin guide](/guides/plugins) to learn
+about conditional plugins
+
+:::