GRUB 2 BIOS BOOT Followup

[zeha]

• boot help texts need rewriting & reformatting, would be good to have most things fit on one "pager screen". Review help&info texts in grub boot menu #296
• make grml2usb work OOTB
• document grml2usb workaround for old grml2usb in release notes
• prepare release notes text / faq update?
• replace pxelinux in netboot packages and in terminalserver with grub, GRUB: consider netboot modules #485
• grub: drop loading of efi_uga module #484

[mika]

FTR, I seem to have managed to get grml2usb/grml2iso working for amd64/arm64 with GRUB-only, will try to finish my work and provide a PR in the upcoming days, this should also fix our failing grml2usb actions.