Fix MyRefCounted example

[bclewi]

The example for making a class MyRefCounted did not pass the same class to the GDCLASS macro despite that appearing to be required based on the first example shown. I am new to C++ and just started learning how to contribute, so it is possible that I am missing something.

First example - passes CustomObject (same class) to GDCLASS

class CustomObject : public Object {
	GDCLASS(CustomObject, Object); // This is required to inherit from Object.
};

https://docs.godotengine.org/en/latest/engine_details/architecture/object_class.html#general-definition

Example in question - passes MyReference (different class) instead of MyRefCounted to GDCLASS

class MyRefCounted: public RefCounted {
  GDCLASS(MyReference, RefCounted);
};

https://docs.godotengine.org/en/latest/engine_details/architecture/object_class.html#refcounted-memory-management

[Mickeon]

You're not missing anything. Reference is the equivalent class in Godot 3.x before it was renamed.