Add content for client-side caching (#2689)

* Added client-side-file-caching

There was no data on client-side-file-caching, so I added some for people to learn.

* Update content/roadmaps/101-backend/content/110-caching/102-client-side.md

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

content/roadmaps/101-backend/content/110-caching/102-client-side.md

@@ -1 +1,5 @@
-# Client side
+# Client Side Caching
+
+Client-side caching is the storage of network data to a local cache for future re-use. After an application fetches network data, it stores that resource in a local cache. Once a resource has been cached, the browser uses the cache on future requests for that resource to boost performance.
+
+<BadgeLink colorScheme='red' badgeText='Watch' href='https://www.youtube.com/watch?v=HiBDZgTNpXY'>Everything you need to know about HTTP Caching</BadgeLink>