SW: update README and firmware-build.sh for mikroBUS
- Added mikroBUS over Greybus Submodule
- Updated README for mikroBUS over Greybus instructions and updated FW build script for building examples for SensorTag and CC1352R Launcpad, and also instructions for trying different clicks and describing devices over Zephyr DT
https://github.com/jadonk/beagleconnect/issues/48 https://github.com/jadonk/beagleconnect/issues/19