Added content to data structure readme.md (#2325)

* Added content to data structure readme.md

Added basic understanding of data structures with a free-read content

* Update readme.md

* Update content/roadmaps/106-javascript/content/104-javascript-data-structures/readme.md

* Update content/roadmaps/106-javascript/content/104-javascript-data-structures/readme.md

Co-authored-by: Kamran Ahmed <kamranahmed.se@gmail.com>

content/roadmaps/106-javascript/content/104-javascript-data-structures/readme.md

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-# Javascript data structures
+# Data Structures
+
+A Data structure is a format to organize, manage and store data in a way that allows efficient access and modification. JavaScript has primitive (built-in) and non-primitive (not built-in) data structures. Primitive data structures come by default with the programming language and you can implement them out of the box (like arrays and objects). Non-primitive data structures don't come by default and you have to code them up if you want to use them.
+
+<ResourceGroupTitle>Free Content</ResourceGroupTitle>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.freecodecamp.org/news/data-structures-in-javascript-with-examples/#what-is-a-data-structure'> Data structures</BadgeLink>