Missing documentation for new eye tracking component API

[risa2000]

The latest release added few new things related to eye tracking support in OpenXR (via SteamVR runtime), which are part of IVRDriverInput interface:

struct VREyeTrackingData_t
{
	bool bActive;
	bool bValid;
	bool bTracked;

	vr::HmdVector3_t vGazeOrigin;  // Ray origin
	vr::HmdVector3_t vGazeTarget;  // Gaze target (fixation point)
};

for the "eye pose" and

/** Creates an eye tracking component **/
virtual EVRInputError CreateEyeTrackingComponent( PropertyContainerHandle_t ulContainer, const char *pchName, VRInputComponentHandle_t *pHandle ) = 0;

/** Updates an eye tracking component. */
virtual EVRInputError UpdateEyeTrackingComponent( VRInputComponentHandle_t ulComponent, const VREyeTrackingData_t *pEyeTrackingData, double fTimeOffset ) = 0;

for the API.

Please add a documentation on the eye pose structure:

• What is difference between all different bool flags?
• To which "tracking space" are the two vectors related (world space, headpose space, something else)?

For IVRDriverInput API, explain:

• What are the expected/allowed component names in CreateEyeTrackingComponent and how many components are supported?
• What is the purpose of fTimeOffset - which time unit, which time domain?

So far, some essential information, but not all, is only available here:
https://github.com/mbucchia/Pimax-EyeTracker-SteamVR