Update free-courses-en.md (#8303)

* Update free-courses-en.md

Added System Design course

* Update free-courses-hi.md

Removed English course from Hindi resources

courses/free-courses-en.md

@@ -348,6 +348,7 @@
 * [MIT's Introduction to Computer Science and Programming](https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-00sc-introduction-to-computer-science-and-programming-spring-2011/) - John Guttag (MIT OpenCourseWare)
 * [MIT's Introduction to Computer Science and Programming in Python](https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and-programming-in-python-fall-2016/) - Ana Bell, Eric Grimson, John Guttag (MIT OpenCourseWare)
 * [MIT's Mathematics for Computer Science](http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-042j-mathematics-for-computer-science-fall-2010/video-lectures/)
+* [System Design](https://www.youtube.com/playlist?list=PLMCXHnjXnTnvo6alSjVkgxV-VH6EPyvoX) - Gaurav Sen
 
 
 ### Cuda

courses/free-courses-hi.md

@@ -406,7 +406,6 @@
 ### System Design
 
 * [System Analysis and Design](https://www.youtube.com/playlist?list=PLi81x6d2Os_8Sa8HifiFruWK6wmgG3Wrg) - Gursimran Singh Dhillon
-* [System Design](https://www.youtube.com/playlist?list=PLMCXHnjXnTnvo6alSjVkgxV-VH6EPyvoX) - Gaurav Sen
 * [System Design Primer Course](https://www.youtube.com/playlist?list=PLTCrU9sGyburBw9wNOHebv9SjlE4Elv5a) - sudoCODE