Clarify in RigidBody2D Documentation That Scaling Is Overwritten

[KlugeNico]

Your Godot version:

4.3

Issue description:

The documentation for RigidBody2D does not mention that any scaling applied to a RigidBody2D will be overwritten by the physics engine. This can lead to confusion for developers attempting to scale RigidBody2D nodes.

Including this information in the documentation would help clarify the behavior and prevent potential misunderstandings.

URL to the documentation page (if applicable):

https://docs.godotengine.org/en/stable/classes/class_rigidbody2d.html

[KlugeNico]

godotengine/godot#89898