README.md: add instructions for softdevice (#129)
README.md: add instructions for softdevice (#129)

* README.md: add instructions for softdevice

* README.md: add instructions for softdevice

* Update README.md

sandeepmistry/arduino-BLEPeripheral,sandeepmistry/arduino-BLEPeripheral,sandeepmistry/arduino-BLEPeripheral