Add Docusaurus markdown features

Basic framing, requires personalization

CONTRIBUTING.md

@@ -84,3 +84,106 @@ When linking between pages in the docs, we use the local (`../../page.mdx#sectio
 Relevantly, if you're referencing the summary or menu page for a subsection, it's likely the file you're looking for is in `parent/README.mdx` rather than `folder.mdx`. And of course 
 
 [^astrodollar]: In code examples, it's common practice to use astroDollars (and astroPesos if two are needed) as generic tokens.
+
+---
+
+# Docusarus markdown features
+
+## Front Matter
+
+Markdown documents have metadata at the top called [Front Matter](https://jekyllrb.com/docs/front-matter/):
+
+```text title="my-doc.md"
+// highlight-start
+---
+id: my-doc-id
+title: My document title
+description: My document description
+slug: /my-custom-url
+---
+// highlight-end
+
+## Markdown heading
+
+Markdown text with [links](./hello.md)
+```
+
+## Links
+
+Regular Markdown links are supported, using url paths or relative file paths.
+
+```md
+Let's see how to [Create a page](/create-a-page).
+```
+
+```md
+Let's see how to [Create a page](./create-a-page.md).
+```
+
+**Result:** Let's see how to [Create a page](./create-a-page.md).
+
+## Images
+
+Regular Markdown images are supported.
+
+You can use absolute paths to reference images in the static directory (`static/img/docusaurus.png`):
+
+```md
+![Docusaurus logo](/img/docusaurus.png)
+```
+
+![Docusaurus logo](/img/docusaurus.png)
+
+You can reference images relative to the current file as well. This is particularly useful to colocate images close to the Markdown files using them:
+
+```md
+![Docusaurus logo](./img/docusaurus.png)
+```
+
+## Code Blocks
+
+Markdown code blocks are supported with Syntax highlighting.
+
+````md
+```jsx title="src/components/HelloDocusaurus.js"
+function HelloDocusaurus() {
+  return <h1>Hello, Docusaurus!</h1>;
+}
+```
+````
+
+```jsx title="src/components/HelloDocusaurus.js"
+function HelloDocusaurus() {
+  return <h1>Hello, Docusaurus!</h1>;
+}
+```
+
+## Admonitions
+
+Docusaurus has a special syntax to create admonitions and callouts:
+
+```md
+:::tip My tip
+
+Use this awesome feature option
+
+:::
+
+:::danger Take care
+
+This action is dangerous
+
+:::
+```
+
+:::tip My tip
+
+Use this awesome feature option
+
+:::
+
+:::danger Take care
+
+This action is dangerous
+
+:::