RigidDynamicBody2D referenced but not in 4.0b

[Black-Virtue]

Your Godot version: 4.0b

Issue description: Documentation lists non-existant type

URL to the documentation page: https://docs.godotengine.org/en/latest/getting_started/first_2d_game/04.creating_the_enemy.html

Documentation references RigidDynamicBody2D, only RigidBody2D exists in 4.0b. Unsure if this is a feature yet to be included or documentation referencing to a name in flux.

[Calinou]

RigidDynamicBody2D was renamed back to RigidBody2D recently: https://github.com/godotengine/godot-proposals/issues/5183