Add SECURITY section to loader(8)

[trasz]

Summary

Add SECURITY section to loader(8).

[bcr]

Update the .Dd at the top of the file for this content change.
Thanks for working on this.

[trasz]

Also update init(8).

[imp]

Looks great.

[jilles]

This is useful, but some parts seem too specific to usage in appliances.

stand/man/loader.8

968–975 ↗

(On Diff #46619)

This recommendation seems geared towards appliances and kiosk type devices; PCs and servers tend not to be secured this way (if firmware and /etc/ttys are not secured along with loader, securing loader mostly makes it harder to recover from breakage and does not improve security).

Perhaps this can be changed to just mention that setting .Va password or setting .Va autoboot_delay to -1 can prevent unauthorized access to the loader command line.

[trasz]

Tone it down somewhat, mention the firmware.

[bcr]

Looks good. Don't forget the .Dd bump.