ocs_fc.4: Cleanup

+ more consistent document description
+ enumerate available options in synopsis in vt.4 style
+ tag spdx
+ tweak list rendering
+ cleanup HARDWARE
+ reflow excessively long lines silencing linter warnings
+ fix link macros

MFC after: 3 days
Reported by: michaelo (hardware notes)
Differential Revision: https://reviews.freebsd.org/D56753

(cherry picked from commit dd97c3d83f9a92bbeb9740ceff4c1c74c451293e)