docs: admin-guide: Update bootloader and installation instructions
Updates the bootloader and installation instructions in
admin-guide/README.rst to align with modern practices.
Details of Changes:
- Added guidance on using EFISTUB for UEFI/EFI systems.
- Noted that LILO is no longer in active development and provides
alternatives.
- Kept LILO instructions but marked as Legacy LILO Instructions.
Suggest removal in future patch.
Signed-off-by: Hunter Chasens <hunter.chasens18@ncf.edu>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
[jc: repaired added whitespace warnings]
Link: https://lore.kernel.org/r/20240207171007.45405-1-hunter.chasens18@ncf.edu