Added a game development course by freecodecamp (#11439)

* Added a game development course by freecodecamp

* Update free-courses-en.md

courses/free-courses-en.md

@@ -748,6 +748,7 @@
 * [Godot Action RPG Series](https://www.youtube.com/playlist?list=PL9FzW-m48fn2SlrW0KoLT4n5egNdX-W9a) - HeartBeast
 * [Godot Space Sidescroller Tutorial Series](https://www.youtube.com/playlist?list=PL6bQeQE-ybqAzXZlZCiRKCtu6RbkXLgmh) - PlugWorld
 * [Godot Wave Shooter Tutorials](https://www.youtube.com/playlist?list=PL6bQeQE-ybqAYoaWz_ZEE2X4wX6PhwCWR) - PlugWorld
+* [Learn Unity - Beginner's Game Development Tutorial](https://www.youtube.com/watch?v=gB1F9G0JXOo) - freeCodeCamp.org
 * [Low Poly Art For Video Games](https://www.coursera.org/learn/low-poly-art-video-games) - Andrew Dennis, Ricardo Guimaraes (Coursera)
 * [Make a Platform Shooter - GameMaker Studio 2](https://www.youtube.com/playlist?list=PL9FzW-m48fn3Ya8QUTsqU-SU6-UGEqhx6) - HeartBeast
 * [Multiplayer Shooter Tutorials - Godot](https://www.youtube.com/playlist?list=PL6bQeQE-ybqDmGuN7Nz4ZbTAqyCMyEHQa) - PlugWorld