docs: improve publicAssets config details (#1102)

docs/content/3.config.md

@@ -98,6 +98,22 @@ Public asset directories to serve in development and bundle in production.
 
 If a `public/` directory is detected, it will be added by default, but you can add more by yourself too!
 
+It's possible to set Cache-Control headers for assets using the `maxAge` option:
+```
+  publicAssets: [
+    {
+      baseURL: "images",
+      dir: "public/images",
+      maxAge: 60 * 60 * 24 * 7, // 7 days
+    },
+  ],
+```
+The config above generates the following header in the assets under `public/images/` folder:
+
+`cache-control: public, max-age=604800, immutable`
+
+
+
 ### `compressPublicAssets`
 
 - Default: `{ gzip: false, brotli: false }`{lang=ts}