Use `GDREGISTER` defines in example

(cherry picked from commit a537b4af4ded29ee715a950f47887cb5367b9825)

README.md

@@ -131,7 +131,7 @@ void initialize_example_module(ModuleInitializationLevel p_level) {
 	if (p_level != MODULE_INITIALIZATION_LEVEL_SCENE) {
 		return;
 	}
-	ClassDB::register_class<Example>();
+	GDREGISTER_CLASS(Example);
 }
 ```
 

test/src/register_types.cpp

@@ -21,13 +21,13 @@ void initialize_example_module(ModuleInitializationLevel p_level) {
 		return;
 	}
 
-	ClassDB::register_class<ExampleRef>();
-	ClassDB::register_class<ExampleMin>();
-	ClassDB::register_class<Example>();
-	ClassDB::register_class<ExampleVirtual>(true);
-	ClassDB::register_abstract_class<ExampleAbstract>();
-	ClassDB::register_class<ExampleBase>();
-	ClassDB::register_class<ExampleChild>();
+	GDREGISTER_CLASS(ExampleRef);
+	GDREGISTER_CLASS(ExampleMin);
+	GDREGISTER_CLASS(Example);
+	GDREGISTER_VIRTUAL_CLASS(ExampleVirtual);
+	GDREGISTER_ABSTRACT_CLASS(ExampleAbstract);
+	GDREGISTER_CLASS(ExampleBase);
+	GDREGISTER_CLASS(ExampleChild);
 }
 
 void uninitialize_example_module(ModuleInitializationLevel p_level) {