chore(Settings): ensure the SteamVR script define is set in the project
chore(Settings): ensure the SteamVR script define is set in the project

As the examples all use the SteamVR SDK by default, it's worth having
the SteamVR script define set as standard in the project settings.

This should prevent unwanted errors for people trying the repo for the
first time.

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