Fix typo (#7198)

Author: swaminator

src/pages/[platform]/build-a-backend/storage/define-storage/index.mdx

@@ -113,7 +113,7 @@ export const storage = defineStorage({
   name: 'myProjectFiles',
   access: (allow) => ({
     'public/*': [
-      allow.guest.to(['read'])
+      allow.guest.to(['read']),
       allow.authenticated.to(['read', 'write', 'delete']),
     ],
     'protected/{entity_id}/*': [