Update README.md (#1248)
Update README.md (#1248)

it wasn't clear, if all or only the statechart tool was required. (see instruction point 8)
Yakindu/statecharts,Yakindu/statecharts,Yakindu/statecharts,Yakindu/statecharts,Yakindu/statecharts,Yakindu/statecharts,Yakindu/statecharts