Manually tuning ZFS for systems with <8GB ram hasn't been necessary at
least since the switch to OpenZFS. We have users reporting using 2GB RAM
with no manual tuning/issues. Further, the page this links to is a stale
wiki page, which is causing user complaints. Remove this misleading note
and replace it with a similar message for UFS. While here, reword that
note to be a bit clearer.

Possible TODO, replace both with something like:
ZFS:
"An advanced filesystem with built-in compression and error correction"
UFS:
"A traditional filesystem with unparaleled simplicity and speed"

PR: 287719