usb(4): manpage cleanup

1. Wrap at <80 columns for readability when editing. Rewrap some lines prematurely wrapped to better fit in <80 columns and not waste vertical space.
2. Fix SEE ALSO sorting (sort by section first, then manpage name).
3. Tweak the compound device description slightly by adding soft stops via commas.

MFC after: 1 week
Reported by: igor [3], manlint [2]
Sponsored by Dell EMC Isilon