update markdown in notes.md files to remove improper display of references

Author: computer0101

graphs/notes.md

@@ -62,6 +62,8 @@ Traversals:
 
 4. **Topological Sorting**: Dependencies of packages can be represented using graphs and those packages are compiled first which have no dependenies or have dependencies but these have already been compiled.
 
-<br>
-*References*:
-* [https://en.wikipedia.org/wiki/Graph_(abstract_data_type)](https://en.wikipedia.org/wiki/Graph_(abstract_data_type))
+<br/>
+
+_References_:
+
+- [https://en.wikipedia.org/wiki/Graph\_(abstract_data_type)](https://en.wikipedia.org/wiki/Graph_(abstract_data_type))

linked_lists/circular_doubly_ll/notes.md

@@ -11,6 +11,8 @@ It is the combine version of circular and doubly linked list where each node poi
 5. Delete − Deletes an element using the given key.
 6. Reverse - Reverses the linked list.
 
-<br>
-*References*:
-[https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list](https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list)
+<br/>
+
+_References_:
+
+- [https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list](https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list)

linked_lists/circular_ll/notes.md

@@ -11,6 +11,8 @@ In the last node of a list, the link field often contains a null reference, a sp
 5. Delete − Deletes an element using the given key.
 6. Reverse - Reverses the linked list.
 
-<br>
-*References*:
-[https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list](https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list)
+<br/>
+
+_References_:
+
+- [https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list](https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list)

linked_lists/doubly_ll/notes.md

@@ -13,6 +13,8 @@ Many modern operating systems use doubly linked lists to maintain references to
 5. Delete − Deletes an element using the given key.
 6. Reverse - Reverses the linked list.
 
-<br>
-*References*:
-* [https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list](https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list)
+<br/>
+
+_References_:
+
+- [https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list](https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list)

linked_lists/notes.md

@@ -32,8 +32,10 @@ A drawback of linked lists is that access time is linear (and difficult to pipel
   - Θ(n) when last element is unknown
 - Insert/Delete in middle: search time + Θ(1)
 
-<br>
-*References*:
-* [https://en.wikipedia.org/wiki/Linked_list](https://en.wikipedia.org/wiki/Linked_list)
-* [https://www.quora.com/What-is-an-application-of-linear-linked-list-data-structures](https://www.quora.com/What-is-an-application-of-linear-linked-list-data-structures)
-* [https://www.geeksforgeeks.org/applications-of-linked-list-data-structure/](https://www.geeksforgeeks.org/applications-of-linked-list-data-structure/)
+<br/>
+
+_References_:
+
+- [https://en.wikipedia.org/wiki/Linked_list](https://en.wikipedia.org/wiki/Linked_list)
+- [https://www.quora.com/What-is-an-application-of-linear-linked-list-data-structures](https://www.quora.com/What-is-an-application-of-linear-linked-list-data-structures)
+- [https://www.geeksforgeeks.org/applications-of-linked-list-data-structure/](https://www.geeksforgeeks.org/applications-of-linked-list-data-structure/)

linked_lists/single_ll/notes.md

@@ -11,7 +11,9 @@ Singly linked lists contain nodes which have a data field as well as 'next' fiel
 5. Delete − Deletes an element using the given key.
 6. Reverse - Reverses the linked list.
 
-<br>
-*References*:
-[https://www.tutorialspoint.com/data_structures_algorithms/linked_list_algorithms.htm](https://www.tutorialspoint.com/data_structures_algorithms/linked_list_algorithms.htm)
-[https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list](https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list)
+<br/>
+
+_References_:
+
+- [https://www.tutorialspoint.com/data_structures_algorithms/linked_list_algorithms.htm](https://www.tutorialspoint.com/data_structures_algorithms/linked_list_algorithms.htm)
+- [https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list](https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list)