Add Astro to site generator docs

Closes GH-2118.

Reviewed-by: Titus Wormer <tituswormer@gmail.com>
Reviewed-by: Sarah Rainsberger <sarah@rainsberger.ca>

Co-authored-by: Titus Wormer <tituswormer@gmail.com>
Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>

Author: 3 people

docs/docs/getting-started.server.mdx

@@ -481,6 +481,25 @@ Which in turn lets us choose whether to use the `@mdx-js/mdx` or
 
 ### Site generators
 
+#### Astro
+
+[Astro](https://astro.build/) has an [official MDX integration](https://docs.astro.build/guides/integrations-guide/mdx/).
+You can add the integration with the Astro CLI (recommended):
+
+```sh
+npx astro add mdx
+```
+
+This base setup allows you to import markdown, Astro components,
+and other MDX files as components.  To use
+other UI framework components in your MDX files
+(e.g. Preact, Vue, Svelte and more),
+see Astro’s [Framework components](https://docs.astro.build/en/core-concepts/framework-components/) guide.
+
+To learn how to configure layouts, YAML frontmatter, and set up Astro’s
+syntax highlighting, [see their MDX
+integration docs](https://docs.astro.build/guides/integrations-guide/mdx/).
+
 #### Create React App (CRA)
 
 <Note type="info">