Add PROTON_USE_VKD3D to vars

data_from_portwine/scripts/vars

@@ -38,6 +38,7 @@ else        ###DXVK###
     export __GL_SYNC_TO_VBLANK=1
     export PROTON_USE_WINED3D=0
     export PROTON_USE_D9VK=1
+#    export PROTON_USE_VKD3D=0
     export PROTON_NO_D3D11=0
     export PROTON_NO_D3D10=0
     export PROTON_OLD_GL_STRING=0