Update free-courses-en.md (#4744)

* Update free-programming-books.md

* Update free-courses-en.md

* Update free-programming-books.md

* Apply suggestions from code review
Co-authored-by: NSeth <seth@elypia.org>
Co-authored-by: NSeth <seth@elypia.org>

free-courses-en.md

@@ -557,6 +557,7 @@
 
 * [Ethical Hacking](https://www.hacker101.com/videos) -(Hacker101)
 * [The Complete Cyber Security & Hacking Course](https://academy.ehacking.net/p/cyber-security-training-hacking-course) -(Insec Techs- EH Academy)
+* [Zero to Hero: A Practical Network Penetration Testing Course](https://www.youtube.com/playlist?list=PLLKT__MCUeiwBa7d7F_vN1GUwz_2TmVQj) - The Cyber Mentor
 
 
 ### Software Engineering