separate declaration and implementation

data/www/index.html

@@ -23,6 +23,10 @@
         <span class="heading">System</span>
         <div class="content">
           <div><label>Free Heap: </label><span class="js-heap"></span><span>&nbsp;bytes</span><br><br></div>
+          <form method='POST' action='/update' enctype='multipart/form-data'>
+            <input type='file' name='update'><input type='submit' value='Update'>
+          </form>
+          <br>
           <button class="js-restart">Restart</button>
         </div>
       </div>