Update free-courses-ar.md (#10555)

* Update free-courses-ar.md

adding more courses on operating system

* Update free-courses-ar.md

* Update free-courses-ar.md

* Update free-courses-ar.md

Author: Adamkaram

Diff for: courses/free-courses-ar.md

@@ -406,7 +406,10 @@
 
 ### Operating Systems
 
+* [Linux System‏](https://www.youtube.com/playlist?list=PL8pYI62gCNsWTppELEUCpforC4avEiLox) - anahr
+* [Operating Systems - أنظمة التشغيل](https://www.youtube.com/playlist?list=PLxIvc-MGOs6ib0oK1z9C46DeKd9rRcSMY) - Ahmed Hagag
 * [Operating Systems - نظم التشغيل](https://www.youtube.com/playlist?list=PLMm8EjqH1EFV-jECqtMxeVMDoVkV_kJDY) - Ahmed Sallam
+* [Operating Systems in Arabic - شرح نظم التشغيل](https://www.youtube.com/playlist?list=PLTr1xN4uMK5seRz6IO7Am9Zp2UKdnzO_n) - Mohamed Alsayed
 
 
 ### PHP