add french c++ course (#6181)

* add french c++ course

* fix blankline linting

* Update courses/free-courses-fr.md

Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

* add to index

Co-authored-by: x0rld <git@x0rld.eu>
Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

courses/free-courses-fr.md

@@ -4,6 +4,7 @@
 * [Bash / Shell](#bash--shell)
 * [C](#c)
 * [C#](#c-sharp)
+* [C++](#cpp)
 * [Git](#git)
 * [HTML / CSS](#html--css)
 * [Java](#java)
@@ -39,6 +40,11 @@
 * [TUTOS C](https://www.youtube.com/playlist?list=PLEagTQfI6nPOWS4JPnxW5pRVgeyLuS5oC) - PrimFX
 
 
+### <a name="cpp"></a>C++
+
+* [La programmation en C++ moderne](https://zestedesavoir.com/tutoriels/822/la-programmation-en-c-moderne/) - Zeste de savoir informaticienzero mehdidou99
+
+
 ### C Sharp
 
 * [C# - Cours](https://www.youtube.com/playlist?list=PLrSOXFDHBtfGBHAMEg9Om9nF_7R7h5mO7) - Formation Video