`unitialize_example_model` in GDExtension example looks suspiciously like a no-op

**Your Godot version:**
master
**Issue description:**
The [GDExtension C++ example](https://github.com/godotengine/godot-docs/blob/d0fde25f53d99d7b4aa0ed49f915d3e2e7efee55/tutorials/scripting/gdextension/gdextension_cpp_example.rst?plain=1#L275) gives this rather odd example for `uninitialize_example_model` in `register_types.cpp`:
```
void uninitialize_example_module(ModuleInitializationLevel p_level) {
if (p_level != MODULE_INITIALIZATION_LEVEL_SCENE) {
return;
}
}
```
This looks a lot like a function that checks for a specific module initialization level, but then returns without doing anything either way? Is this intentional? Is this function actually necessary here? If it is, the documentation should really say something about it, as it's rather confusing as it is now. If there is some uninitialization code that would be needed in other circumstances but isn't needed here, the documentation should really include some examples of when it would be needed.

**URL to the documentation page (if already existing):**
https://github.com/godotengine/godot-docs/blob/d0fde25f53d99d7b4aa0ed49f915d3e2e7efee55/tutorials/scripting/gdextension/gdextension_cpp_example.rst?plain=1#L275