updated readme and example

ready for review @TiddoLangerak 
Well, but if you leave it out there is *also* a fail scenario in place, you'll get exactly the same error if there isn't a single `sp` key as when there are just a few `sp` keys. Additionally, IMO a demo should be the most simple fully *working* version. Having failing scenarios in there only confuses things (I would not expect a demo to be not working).