add button functionality

Author: Supravisor

index.html

@@ -23,7 +23,7 @@ <h2>Diff checker</h2>
     </div>
 
     <div id="buttons">
-      <button id="button-original">Hide Original</button>
+      <button id="button-original" onclick="original()">Hide Original</button>
       <button id="button-compare">Hide Compare</button>
     </div>