Incorrect documentation for Transform2D

**Your Godot version:**
4.3

**Issue description:**
The documentation for `Transform2D.IDENTITY` states that "The y points up (`Vector2.UP`)", but is set to `Vector2.DOWN`.

**URL to the documentation page:**
https://docs.godotengine.org/en/stable/classes/class_transform2d.html#class-transform2d-constant-identity