Add information about licensing, both the cyw43-driver and the btstack driver (for commercial and non-commercial uses) when used with Pico or Pico W, or with a bare RP2040.

Normal BTStack license, https://github.com/bluekitchen/btstack/blob/master/LICENSE
The RP version, https://github.com/raspberrypi/pico-sdk/blob/master/src/rp2_common/pico_btstack/LICENSE.RP

The normal cyw43-driver license, https://github.com/georgerobotics/cyw43-driver/blob/main/LICENSE
The RP version, https://github.com/georgerobotics/cyw43-driver/blob/main/LICENSE.RP