Update 101-linked-lists.md

Added a link to an article which helped me understand more about the concept of linked list.

src/data/roadmaps/datastructures-and-algorithms/content/103-basic-data-structures/101-linked-lists.md

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 # Linked Lists
 
-Linked Lists are a type of data structure used for storing collections of data. The data is stored in nodes, each of which contains a data field and a reference (link) to the next node in the sequence. Structurally, a linked list is organized into a sequence or chain of nodes, hence the name. Two types of linked lists are commonly used: singly linked lists, where each node points to the next node and the last node points to null, and doubly linked lists, where each node has two links, one to the previous node and another one to the next. Linked Lists are used in other types of data structures like stacks and queues.
+Linked Lists are a type of data structure used for storing collections of data. The data is stored in nodes, each of which contains a data field and a reference (link) to the next node in the sequence. Structurally, a linked list is organized into a sequence or chain of nodes, hence the name. Two types of linked lists are commonly used: singly linked lists, where each node points to the next node and the last node points to null, and doubly linked lists, where each node has two links, one to the previous node and another one to the next. Linked Lists are used in other types of data structures like stacks and queues.
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+[A beginner's guide to linked-list](https://www.freecodecamp.org/news/how-linked-lists-work/)