[Dev] UEFI wiki need some love

https://github.com/96boards/documentation/wiki/UEFI

Trying to get UEFI booting via this wiki didn't really work well. I had to check with several others to get things actually working.

A couple major things I found in the last day or so:

1) it mentions the ptable.img file, but doesn't say where to find it

2) It mentions starting fastboot from UEFI, which requires your boot-uefi.img have a fastboot application on it. However, the wiki guides you through creating a boot-uefi.img with a kernel/dtb/initrd but no fastboot.efi, so trying to start fastboot from the shell doesn't work.

Kevin