docs: change config snippets to use defineConfig (#7546)

www/apps/resources/app/architectural-modules/notification/page.mdx

@@ -30,7 +30,11 @@ When you send a notification, you specify the channel to send it through, such a
 
 For example:
 
-```js title="medusa-config.js" highlights={[["15"]]}
+```js title="medusa-config.js" highlights={[["19"]]}
+const { Modules } = require("@medusajs/modules-sdk")
+
+// ...
+
 module.exports = {
   // ...
   modules: {