Update free-courses-en.md (#9605)

* Update free-courses-en.md

Added ASP.NET Core 2.2 & 3 REST API Tutorial link in C#

* Fix issue 

Alphabetically arrange the resource.

courses/free-courses-en.md

@@ -314,6 +314,7 @@
 
 ### <a id="csharp"></a>C\#
 
+* [ASP.NET Core 2.2 & 3 REST API Tutorial](https://youtube.com/playlist?list=PLUOequmGnXxOgmSDWU7Tl6iQTsOtyjtwU&si=3XHU6BnqwxePAt54) - Nick Chapsas
 * [Building a microservice architecture with ASP.NET Core - Gill Cleeren - NDC London 2022](https://www.youtube.com/watch?v=SR53SKIUYPA) - Gill Cleeren
 * [C# 101](https://channel9.msdn.com/Series/CSharp-101) - Scott Hanselman, Kendra Havens (Microsoft)
 * [C# Programming All-in-One Tutorial Series (6 HOURS!)](https://www.youtube.com/watch?v=qOruiBrXlAw) - Caleb Curry