update readme

Author: David-Desmaisons

README.md

@@ -267,6 +267,6 @@ https://jsfiddle.net/dede89/L54yu3L9/
 <script src="//cdnjs.cloudflare.com/ajax/libs/Sortable/1.6.0/Sortable.min.js"></script>
 
 <!-- CDNJS :: Vue.Draggable (https://cdnjs.com/) -->
-<script src="//cdnjs.cloudflare.com/ajax/libs/Vue.Draggable/2.12.0/vuedraggable.min.js"></script>
+<script src="//cdnjs.cloudflare.com/ajax/libs/Vue.Draggable/2.13.0/vuedraggable.min.js"></script>
 
 ```