Updated _Footer (markdown)

_Footer.md

@@ -4,4 +4,6 @@
   \|  
 [GitHub](https://github.com/raysan5/raylib "raylib repository on GitHub")
   \|  
-[Discord](https://discord.gg/VkzNHUE)
+[Discord](https://discord.gg/VkzNHUE)
+  \|  
+[YouTube](https://www.youtube.com/c/raylib)