Notify user when WebBT API is missing from bb8 demo
Notify user when WebBT API is missing from bb8 demo

WebBluetoothCG/demos,sowbug/demos,scheib/webbluetoothcg-demos,scheib/webbluetoothcg-demos,WebBluetoothCG/demos,beaufortfrancois/demos,beaufortfrancois/demos,sowbug/demos