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/macros/readme.mdx

@@ -0,0 +1,78 @@
+---
+title: Macros
+---
+
+Macros are a way to combine different operations into a single command.
+Macros are typically provided by by plugins, but can also be added ad-hoc
+without the need for a plugin.
+
+## Signature
+
+```js
+null macro(object config, object props)
+```
+
+A macro receives a single configuration object as its first parameter.
+The second parameter is the same object received by [the draft method in a
+part](/reference/api/part/draft)
+
+## Example
+
+```js
+pattern.use({
+  name: 'My adhoc plugin',
+  macros: {
+    myMacro: function (so, props) {
+      // Do something wonderful here
+    },
+    myOtherMacro: function (so, props) {
+      // Do something wonderful here
+    },
+  }
+}
+```
+
+Now you can use these macros in your part:
+
+```js
+({ macro, part }) => {
+
+  macro('myMacro', {
+    some: [ 'config', 'here' ],
+    more: 'config'
+  })
+  macro('myOtherMacro', 'Just a string')
+
+  return part
+}
+```
+
+## Removing macros and the role of the macro id
+
+Many macros accept an `id` parameter as part of their configuration.  This `id`
+is used to generate the names for paths, points, or snippets that are added to
+the part by the macro.  This way, macro-added content is deterministic, and can
+be removed again.
+
+Each macro typically has an `rm`-prefixed counterpart that removes the (changed
+done by) the macro.  For example, you can add a bartack with the `bartack`
+macro, and it can be removed with the `rmbartack` macro.  For this removal to
+work, and id must be set in the macro, and it must be passed when removing the
+macro.
+
+For macros that are typically used once per part (such as the `title` macro)
+you can rely on the default id.  For macros typically used multiple times (such
+as the various dimension macros) you should set an id that is unique within the
+part for each invocation.
+
+## Macros we maintain
+
+Below is a list of macros from [the plugins we maintain](/reference/plugins).
+
+:::note
+
+We use camelCase here, but macro names are case-insensitive
+:::
+
+<ReadMore />
+