Merge pull request #484 from mdxs/patch-1

Fixed typo in documentation of title for Groups

docs/timeline.html

@@ -343,7 +343,7 @@ var groups = [
     <td>title</td>
     <td>String</td>
     <td>none</td>
-    <td>A title for the group, displayed when holding the mouse the groups label.
+    <td>A title for the group, displayed when holding the mouse on the groups label.
       The title can only contain plain text.
     </td>
   </tr>