loader_simp is a much simplified version of loader that will process a
linear sequence of commands from loader.rc. It has neither Forth nor Lua
built in and is much smaller. Document it. This is largely copied from
loader.8 since it implements those built-in commands. Future revisions
will fix this duplication.
Sponsored by: Netflix
Remove all cross references to zfsloader.8 and /boot/zfsloader.
Move ZFS specific info into loader.8.
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D16361