Update 'src/index.html'

Fixed bug on "header-menu.js!onFileChanged()" that was supposed to exist tag id="messages" here.
Introduced, after button "Edit" the line
   <li><span class="level-1" id="messages1">iGeomJS version 2025/03/20</span></li><!-- to be used to launch messages: -->

src/index.html

@@ -43,6 +43,7 @@
                 </ul>
               </li>
               <li><button class="level-1">Edit</button></li>
+              <li><span class="level-1" id="messages1">iGeomJS version 2025/03/20</span></li><!-- to be used to launch messages: -->              
             </ul>
           </div>
           <div class="p-1 flex-fill center">