Update readme to reflect new DFU build process
Update readme to reflect new DFU build process

greatscottgadgets/greatfet,dominicgs/GreatFET-experimental,dominicgs/GreatFET-experimental,greatscottgadgets/greatfet,greatscottgadgets/greatfet,dominicgs/GreatFET-experimental,greatscottgadgets/greatfet