adding the insert animation

lectures/10_linked_lists/README.md

@@ -264,6 +264,8 @@ q -> next = p -> next; // make its successor be the current successor of p
 p -> next = q; // make p's successor be this new node
 ```
 
+- Play this [animation](https://jidongxiao.github.io/CSCI1200-DataStructures/animations/lists/insert/index.html) to see how this code snippet works.
+
 - Note: This code will not work if you want to insert x in a new node at the front of the linked list. Why not?
 
 ## 10.13 Removing a Node from a Singly-Linked List