Add a tutorial series about making a FPS

Add a tutorial series demonstrating how to build a retro first-person
shooter from scratch in Swift by Nick Lockwood.

Author: bobeff

README.md

@@ -578,6 +578,7 @@ To get started, simply fork this repo. Please refer to [CONTRIBUTING.md](CONTRIB
 ## Swift:
 
 - [Hacking with Swift - Learn Swift by doing 39 projects](https://www.hackingwithswift.com/read)
+- [Retro first-person shooter from scratch](https://github.com/nicklockwood/RetroRampage)
 
 ## Additional Resources