MFC 362324:

MFC 362324:

Clean up and improve manual page for fuser(1)

- Mention option's arguments in the list of options (so that now we mention
  "-N system" instead of just "-N").
- Stylize signals and other constants like O_APPEND with Dv.
- Sort options.
- Change indentation width for readability.
- Fix a couple of typos.
- Sort symbols list.
- Use Sy instead of Cm for symbols. They are not command modifiers.
- Use Ex -std in the EXIT STATUS section for consistency with other manual
  pages.
- Use Ql instead of Dq Li for inline code examples as Li has recently been
  deprecated by mdoc.

Reviewed by:	bcr
Differential Revision:	https://reviews.freebsd.org/D25332