ow_temp.4: improve HARDWARE + tag SPDX

Rewrite the hardware support list to a column list for inclusion in the
Hardware Release Notes. This makes clean subsections. Tested in
MANWIDTH 59 and 80. While here, align sysctl list and tag spdx.

Reviewed by: mhorne
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D47707