revert release sandcastle link

Author: jjspace

index.release.html

@@ -90,7 +90,7 @@ <h2>Local links</h2>
               </td>
             </tr>
             <tr>
-              <td><a href="Apps/Sandcastle2/index.html">Sandcastle</a></td>
+              <td><a href="Apps/Sandcastle/index.html">Sandcastle</a></td>
               <td>
                 Cesium's live code editor and example gallery. Browse examples
                 highlighting features of the Cesium API and edit and run them