Ragdoll system documentation is outdated

**Your Godot version:**

4.3

**Issue description:**

The Ragdoll System tutorial is outdated because it refers to `physical_bones_start_simulation()` on presumably the armature, which is deprecated and also doesn't seem to work anymore. Instead, the same function needs to be called on the `PhysicalBoneSimulator3D`. Additionally, the screenshots seem to be outdated too because the generated node tree doesn't look like that in 4.3 anymore.

This issue may also be related to #4837

**URL to the documentation page:**

https://docs.godotengine.org/en/stable/tutorials/physics/ragdoll_system.html
https://github.com/godotengine/godot-docs/blob/4.3/tutorials/physics/ragdoll_system.rst