chore(DOCUMENTATION): auto generate docs for headset velocity
chore(DOCUMENTATION): auto generate docs for headset velocity

The docs have been generated to contain the additional methods in the
SDK for getting headset velocity and angular velocity.

thestonefox/VRTK,thestonefox/SteamVR_Unity_Toolkit,gomez-addams/SteamVR_Unity_Toolkit,gpvigano/VRTK,adamjweaver/VRTK,virror/VRTK,Innoactive/IA-unity-VR-toolkit-VRTK,red-horizon/VRTK,gpvigano/SteamVR_Unity_Toolkit,TMaloteaux/SteamVR_Unity_Toolkit,Fulby/VRTK,mattboy64/SteamVR_Unity_Toolkit