Misunderstanding with get_custom_data

**Your Godot version:**
4.3 dev 6 windows
**Issue description:**
Error in argument description

The documentation states that it is the name of the layer, This is wrong, really the argument is the name of the data


**URL to the documentation page:**
https://docs.godotengine.org/en/latest/classes/class_tiledata.html#class-tiledata-method-get-custom-data

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