Content proposal in C# (fr) and Spring (en) (#11119)

* Content proposal in C# (fr) and Spring (en)

* ref Spring delete + change in alphabetical order of ref C#

courses/free-courses-fr.md

@@ -49,6 +49,7 @@
 
 ### <a id="csharp"></a>C\#
 
+* [Apprendre le C#](https://www.youtube.com/playlist?list=PLkHw7J3J2iapWFUnQmVzsRCU5YxaAWHSY) - Pentiminax
 * [C# - Cours](https://www.youtube.com/playlist?list=PLrSOXFDHBtfGBHAMEg9Om9nF_7R7h5mO7) - Formation Video