Add a guide to orient your hand model under OpenXR specification

[fight4dream]

1. According to the OpenXR Specification,
   a. the tracked position is at the palm centroid
   b. its +X axis away from palm for left hand, -X away from palm for right hand
   c. its +Z runs along the head line of the palm towards thumb/index finger

Additional Context

The OpenXR Specification: 6.3.2. Input subpaths

[thestonefox]

This can also be done by orientating correctly in the TrackedAlias child.

This is also only required I believe if you have your Plugin-Provider set to OpenXR. I think if you have it set to Oculus then it would work naturally on the Quest but obviously not for any other headset.

This PR ExtendRealityLtd/Tilia.Input.UnityInputSystem#39

can also help and use the Device pose as the parent, although it would still require the interactor/avatar to be orientated according to the above post.