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/packages/rehype-jargon/readme.mdx

@@ -0,0 +1,76 @@
+---
+title: rehype-jargon
+---
+
+Published as [@freesewing/rehype-jargon][1], this package provides
+a [Rehype](https://github.com/rehypejs/rehype)
+plugin for adding HTML markup for jargon terms.
+It allows you to use jargon in your markdown/mdx/html content and use
+a centrally managed file of jargon terms and their definitions.
+
+## Installation
+
+```sh
+npm install @freesewing/rehype-jargon
+```
+
+## Usage
+
+In file `jargon.mjs`:
+```js
+export const jargon = {
+  term: '<b>term</b> has this description',
+  term2: 'A <i>differenti</i> description',
+}
+```
+
+In NodeJS:
+```js
+import rehypeJargon from @freesewing/rehype-jargon
+import { jargon } from './jargon.mjs'
+
+...
+   rehypePlugins: [
+     [rehypeJargon, { jargon: jargon }],
+   ],
+```
+
+### Example
+
+Here is an example of _jargon_ in markdown.
+
+
+## Configuration
+
+| Property | Type | Default | Description |
+|----------|------|---------|-------|
+| jargon | Object |      | Key/Value pairs where the key is a jargon term and the value is the jargon description. The description is a string that can contain HTML tags. Required. |
+| transform | Function | (see below) | Given the jargon term and description, returns a string with the final HTML to output. |
+
+### Default transform function
+
+The default `transform` function is:
+```js
+(term, html) =>
+   `<span class="jargon-term">${term}<span class="jargon-info">${html}</span></span>`
+```
+
+The default `transform` function applies these CSS classes:
+- `jargon-term` is applied to jargon terms
+- `jargon-info` is applied to jargon descriptions
+
+You can style your jargon by adding styles to these CSS classes.
+
+## Notes
+
+- Markup will be added to jargon only if the terms are _emphasized_.
+
+- Keys should be in all lowercase characters in the jargon file.
+This is because terms are converted to lowercase before they are matched
+against the jargon file.
+
+- How terms are capitalized does not matter, for the same reason.
+
+- If you use HTML in your jargon descriptions, use only inline elements such as adding bold/italic formatting and inserting links.
+
+[1]: https://www.npmjs.com/package/@freesewing/rehype-jargon