Update README.md

Author: stefanradivojevic

README.md

@@ -7,3 +7,4 @@ https://stefanradivojevic.github.io/jquery-datatables/ (!important: github pages
 ![jquery datatable](https://github.com/stefanradivojevic/jquery-datatables/blob/master/screenshots/contextmenu.jpeg)
 ![bootstrap modal](https://github.com/stefanradivojevic/jquery-datatables/blob/master/screenshots/modal.jpeg)
 ![noty dialog](https://github.com/stefanradivojevic/jquery-datatables/blob/master/screenshots/dialog-noty.jpeg)
+![sketch contextmenu](https://github.com/stefanradivojevic/jquery-datatables/blob/master/screenshots/sketch.jpg)