[Feat] docs/howto: Improve howto-control-rpi-poweredup

[gmacario]

Closes #50

📑 Description

Expand the HOWTO to detect and send commands to the LEGO® Powered Up Bluetooth Hub.

✅ Checks

• [x] My pull request adheres to the code style of this project
• [ ] My code requires changes to the documentation
• [x] I have updated the documentation as required
• [x] All the tests have passed

ℹ Additional Information