display the two images

lectures/10_linked_lists/README.md

@@ -161,6 +161,8 @@ cout << "1st value: " << ll->value << "\n"
 }
 ```
 
+![alt text](linking.png "linking")
+
 ## 10.5 Definition: A Linked List
 
 - The definition is recursive: A linked list is either:
@@ -171,6 +173,8 @@ The pointer’s value will be stored in a variable called head.
 
 ## 10.6 Visualizing Linked Lists
 
+![alt text](linked_list.png "linked list")
+
 - The head pointer variable is drawn with its own box. It is an individual variable. It is important to have a
 separate pointer to the first node, since the “first” node may change.
 - The objects (nodes) that have been dynamically allocated and stored in the linked lists are shown as boxes,