Enabling switchable microSD boot media for TW on Raspberry Pi-3B aarch64

If you’re running Tumbleweed aarch64 on a Raspberry Pi-3B and would like to be able to boot with your microSD drive either in the mmc slot or in a USB adapter, the following How-To may be helpful:

https://forums.opensuse.org/showthread.php/530092-Tumbleweed-aarch64-on-Raspberry-Pi-3B-enabling-switchable-boot-media