#added computer networking course (#7521)

* #added computer networking course

* Update courses/free-courses-en.md

Co-authored-by: Eric Hellman <eric@hellman.net>

Co-authored-by: Eric Hellman <eric@hellman.net>

courses/free-courses-en.md

@@ -291,6 +291,7 @@
 ### Computer Science
 
 * [Berkeley's CS  61A: Taught using SICP](https://archive.org/details/ucberkeley-webcast-PL3E89002AA9B9879E?tab=collection)
+* [Computer Networking - Network Engineering](https://www.youtube.com/watch?v=qiQR5rTSshw) - Brian Ferrill (FreeCodeCamp)
 * [CS50's Introduction to Computer Science](https://cs50.harvard.edu/x/) - David J. Malan (Harvard OpenCourseWare and edX)
 * [LouvainX Paradigms of Computer Programming – Abstraction and Concurrency](https://www.edx.org/course/paradigms-computer-programming-louvainx-louv1-2x-1#!)
 * [LouvainX Paradigms of Computer Programming – Fundamentals](https://www.edx.org/course/paradigms-computer-programming-louvainx-louv1-1x-1)