references to Linux et al boot requirements

[orangecms]

For running LinuxBoot itself from a previous stage

• https://www.kernel.org/doc/html/latest/arch/riscv/boot.html
• https://www.kernel.org/doc/html/latest/arch/arm64/booting.html
• https://www.kernel.org/doc/html/latest/arch/x86/boot.html

Bootloaders running under LinuxBoot

• https://docs.freebsd.org/en/books/arch-handbook/boot/
• https://www.haiku-os.org/guides/booting/