Update Supported Hardware in README.md
Update Supported Hardware in README.md

1. Move Pixhawk Mini to FMUv3, due to it's using Rev.3 chip, has 2MB flash, and fmuv3 bootloader.
2. Add CUAV V5+ to FMUv5
3. Add CUAV v5 nano
4. Add CUAV Pixhack v3 to FMUv3

Make sure is the hardware URL only on user guide master branch or not

krbeverx/Firmware,PX4/Firmware,krbeverx/Firmware,PX4/Firmware,acfloria/Firmware,acfloria/Firmware,krbeverx/Firmware,acfloria/Firmware,PX4/Firmware,PX4/Firmware,acfloria/Firmware,acfloria/Firmware,PX4/Firmware,krbeverx/Firmware,krbeverx/Firmware,krbeverx/Firmware,krbeverx/Firmware,acfloria/Firmware,PX4/Firmware,PX4/Firmware,acfloria/Firmware