GPU Particles lacks info for the Velocity Pivot value

[WagnerGFX]

Godot version

v4.2.beta4

System information

Windows 10.0.19045 - Vulkan (Forward+, Mobile) - GLES3 (Compatibility) - dedicated NVIDIA GeForce GTX 1650 (NVIDIA; 31.0.15.4592) - Intel(R) Core(TM) i7-2600K CPU @ 3.40GHz (8 Threads)

Issue description

Velocity Pivot is used to control the pivot point of Orbit and Radial animated velocities, but the description is currently empty.

Steps to reproduce

You can use the MRP to check the value in action.

Minimal reproduction project

GPUParticle2D Orbit Pivot.zip (from #84220)

[Chubercik]

The missing description ought to be added here:

godot/doc/classes/ParticleProcessMaterial.xml

Lines 386 to 387 in 6afd320

	<member name="velocity_pivot" type="Vector3" setter="set_velocity_pivot" getter="get_velocity_pivot" default="Vector3(0, 0, 0)">
	</member>