feat: add item list with click event to toggle selection

ejercicio3/ejercicio3.js

@@ -1 +1,7 @@
 // Agregar aquí el código javascript
+
+document.getElementById('itemList').addEventListener('click', (event) => {
+    if (event.target.tagName === 'LI') {
+        event.target.classList.toggle('selected');
+    }
+});