Fix missing comma in options-comment horizontalScroll.html

Author: LukasWillin

examples/timeline/other/horizontalScroll.html

@@ -18,7 +18,7 @@ <h1>Timeline horizontal scroll option</h1>
   stack: true,
   horizontalScroll: true,
   // horizontalScrollKey: 'shiftKey', /* If you want to enable both vertical and horizontal scrolling, uncomment this and the line below. */
-  // verticalScroll: true /* Uncomment this line with the line above to allow for both scroll-axis. */
+  // verticalScroll: true, /* Uncomment this line with the line above to allow for both scroll-axis. */
   // horizontalScrollInvert: true, /* Invert the horizontal scroll direction by uncommenting this line. */
   zoomKey: 'ctrlKey',
   maxHeight: 400,