fix: typo in showing cat's name (#731)

Showing ReferenceError: catName is not defined. Use istead cat.name

javascript/oojs/tasks/object-basics/object-basics1-download.html

@@ -46,7 +46,7 @@
     let para1 = document.createElement('p');
     let para2 = document.createElement('p');
 
-    para1.textContent = `The cat's name is ${ catName }.`;
+    para1.textContent = `The cat's name is ${ cat.name }.`;
     para2.textContent = `The cat's color is ${ cat.color }.`;
 
     section.appendChild(para1);