Lichee Pi4A beta version 8/8 no sufficient documentation

Hi,

I just got to opening the the licheepi4a beta and I'm a bit disappointed the beta version has no documentation at all on a lot of things, which is somewhat expected. 

If anyone has a clue on how to switch to sdcard boot that woul be helpful, I'm using a usb serial to ttl too but I can't get that working either.
