Update Godot project file name

README.md

@@ -1,6 +1,6 @@
 # Godot demo projects
 
-Each folder containing an `engine.cfg` file is a demo project meant to
+Each folder containing a `project.godot` file is a demo project meant to
 be used with [Godot Engine](https://godotengine.org), the open source
 2D and 3D game engine.