This directory contains all files related to GRUB configuration.
Define GRUB user. 
- To look at that, edit 01_users file
- Add the highlighted part.
- Basically, we are adding username and password to our GRUB authentication.
- Edit 10_linux file and remove --unrestricted from the document.
- Doing this, we are telling GRUB to do restricted login (with our new username and password)
- To
 reconfigure all GRUB conf files, go to /boot/grub2. 
- Then, make a backup
 copy of a grub.cfg. 
- Then, type grub2-mkconfig -o /boot/grub2/grub.cfg.
- This command will make new GRUB config file, and overwrite the grub.cfg. 
- Then, reboot the machine.
