add backtrace script and improve config file instructions

config/aarch64/desktop-minimal.toml

config/aarch64/server-minimal.toml

config/i686/desktop-minimal.toml

config/i686/desktop.toml

config/i686/dev.toml

config/i686/server-minimal.toml

config/i686/server.toml

config/x86_64/desktop-contain.toml

config/x86_64/desktop-minimal.toml

config/x86_64/desktop.toml

config/x86_64/dev.toml

config/x86_64/server-minimal.toml

config/x86_64/server.toml

scripts/backtrace.sh