KOS can no longer be installed using the script

[retrohead]

KOS can no longer be installed using the script due to config.mk requirements for dc-chain

https://github.com/dreamcastdevs/dreamcast_tutorial/blob/master/01_setup_KOS_toolchain/kos_setup_script.sh

This seems to work for me before running download.sh in the dc-chain folder

cp config.mk.stable.sample config.mk