The Installation Guide should contain a mention of GRUB2 password protection ("insecure bootloader is insecure, set a password for it") and a link to the System Administrator's Guide, where GRUB2 in general is discussed in depth.

There is a mention on how to set up GRUB2 password using the Kickstart Configurator (33.3. Boot Loader Options), but no mention on how to set it up when making a kickstart file without using the Configurator, or during the graphical installation.

Both of these are fairly complicated and don't really fit in the scope of the book, but a mention on the importance of setting up bootloader password and a link to the System Administrator's Guide should be included.