docs: added dbl linkedlist + refactored layout

Author: yeoshuheng

src/dataStructures/linkedList/README.md

@@ -17,6 +17,12 @@ linked lists are stored across memory and are connected to each other via pointe
 
 *Source: BeginnersBook*
 
+## Analysis
+Some common operations involved in a linked list includes looking up elements in a linked list and inserting elements into a linked list.
+
+Searching a linked list requires O(n) time complexity whereas inserting into a linked list from a specified index requires O(n) time complexity.
+
+## Notes / Further Details / Conclusion
 
 ### Memory Requirements & Flexibility
 As a contiguous block of memory must be allocated for an array, its size is fixed.
@@ -32,8 +38,6 @@ we end up needing to store more elements at run time.
 However, linked list gives us the option of adding new nodes at run time based on our requirements, 
 allowing us to allocate memory to store items dynamically, giving us more flexibility.
 
-**Generally, linked list is more memory efficient and flexible than arrays.**
-
 ### Conclusion
 You should aim to use linked list in scenarios where you cannot predict how many elements you need to store
 or if you require constant time insertions to the list.
@@ -45,10 +49,17 @@ It would also be preferred if you are conducting a lot of look up operations.
 The lookup time within a linked list is its biggest issue.
 However, there are variants of linked lists designed to speed up lookup time.
 
-### Double Linked List
+### Doubly Linked List
+
+![Doubly Linked List](https://media.geeksforgeeks.org/wp-content/cdn-uploads/gq/2014/03/DLL1.png)
+
+*Source: GeeksForGeeks*
+
+This is a variant of the linked list with each node containing the pointer to not just the next note, but also the previous node.
 
+Unlike the standard linked list, this allows us to traverse the list in the backwards direction too, this makes it a good data structure to use when implementing undo / redo functions. However, when implementing a doubly linked list, it is vital to ensure that you consider and maintain **both** pointers.
 
-This 
+It is also worth noting that insertion from the front and back of the linked list is a O(1) operation. (Since we now only need to change the pointers in the node.)
 
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