docs(MADEWITHVRTK): add two new steam games to list
docs(MADEWITHVRTK): add two new steam games to list

Sky Sanctuary and Nock: Hidden Arrow have been added.
gomez-addams/SteamVR_Unity_Toolkit,virror/VRTK,gpvigano/VRTK,thestonefox/SteamVR_Unity_Toolkit,Fulby/VRTK,mattboy64/SteamVR_Unity_Toolkit,TMaloteaux/SteamVR_Unity_Toolkit,gpvigano/SteamVR_Unity_Toolkit,red-horizon/VRTK,Innoactive/IA-unity-VR-toolkit-VRTK,thestonefox/VRTK,adamjweaver/VRTK