Add the join

Signed-off-by: macdonst <[email protected]>

app/cookbook/translate-react.md

@@ -60,7 +60,7 @@ const image = <img src={href} />
 const todoList = `<ul>
   ${todos.map((todo) => (
     `<li key="${todo.id}">${todo.text}</li>`
-  ))}
+  ))}.join('')
 </ul>`
 ```