Typo in `XR_FB_face_tracking2`

[Beyley]

XR_FB_face_tracking2 defines the XR_FACE_EXPRESSION2_EYES_LOOK_ blend shapes as follows: XR_FACE_EXPRESSION2_EYES_LOOK_DOWN_L_FB moves the left eyelid consistent with downward gaze.

However the image/name show this blend shape is actually for moving/rotating the eyes, not the eyelids.

[rpavlik-bot]

An issue (number 2515) has been filed to correspond to this issue in the internal Khronos GitLab (Khronos members only: KHR:openxr/openxr#2515 ), to facilitate working group processes.

This GitHub issue will continue to be the main site of discussion.