Update index.html

Author: Andrei Volchenko

school/dom/index.html

@@ -280,7 +280,7 @@ <h2>Element</h2>
               <pre><code class="xml"><div class="wrapper">
     <span>item</span>
 </div></code></pre>
-              <pre><code class="javascript">var innerHTML = '    <span></span>';
+              <pre><code class="javascript">var innerHTML = '    <span>item</span>';
 assert(div.innerHTML === innerHTML);</code></pre>
           </section>
       </section>