Added Neso Academy PlayList on Operating Systems (#7298)

* Added Neso Academy PlayList on Operating Systems

* Update courses/free-courses-en.md

Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

courses/free-courses-en.md

@@ -820,6 +820,7 @@
 
 * [Berkeley's CS 162: Operating Systems and Systems Programming](https://www.youtube.com/watch?v=feAOZuID1HM)
 * [Berkeley's CS 194: What is an Operating System?](http://www.infocobuild.com/education/audio-video-courses/computer-science/cs194-spring2013-berkeley.html)
+* [Operating System](https://www.youtube.com/playlist?list=PLBlnK6fEyqRiVhbXDGLXDk_OQAeuVcp2O) - Neso Academy
 
 
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