Add multiple cdn

src/content/docs/en/reference/configuration-reference.mdx

@@ -492,13 +492,17 @@ Specifies the directory in the build output where Astro-generated assets (bundle
 
 <p>
 
-**Type:** `string`<br />
+**Type:** `string | Record.<string, string>`<br />
 **Default:** `undefined`<br />
 <Since v="2.2.0" />
 </p>
 
 Specifies the prefix for Astro-generated asset links. This can be used if assets are served from a different domain than the current site.
 
+<p>
+**If this value is a `string`,**
+</p>
+
 For example, if this is set to `https://cdn.example.com`, assets will be fetched from `https://cdn.example.com/_astro/...` (regardless of the `base` option).
 You would need to upload the files in `./dist/_astro/` to `https://cdn.example.com/_astro/` to serve the assets.
 The process varies depending on how the third-party domain is hosted.
@@ -512,6 +516,28 @@ To rename the `_astro` path, specify a new directory in `build.assets`.
 }
 ```
 
+<p>
+**If this value is a `Record<string, string>`,**
+</p>
+
+If your static files are served from different CDNs, you can configure Astro to use unique prefix paths for each CDN based on the filetype requested.
+
+For example, if the static file is a `.js` file, it will be served from `https://js.cdn.example.com`. If it is a `.css` file, it will be served from `https://css.cdn.example.com`. All other assets will be served from `https://cdn.example.com`.
+
+```js
+{
+  build: {
+    assetsPrefix: {
+      'js': 'https://js.cdn.example.com',
+      'css': 'https://css.cdn.example.com',
+      'defaultAssetsPrefix': 'https://cdn.example.com'
+    }
+  }
+}
+```
+
+The object key is the file extension, and its value is the CDN prefix path. You can set the default values of all other files by setting the value of `defaultAssetsPrefix`. If `defaultAssetsPrefix` is not set, when the file extension is not found in the `assetsPrefix` object, it will be set to the empty string `''` by default.
+
 ### build.serverEntry
 
 <p>