Clean up fstat.1

• Sort options in the list & indent for readability.
• Pet linters
  • Use "\(em" instead of "--"
  • Remove Tn macros
• Use Ql instead of Dq Li
• Add arguments to the -M, -N, -p, and -u options in their descriptions.
• Use Sy instead of Li for field names. Li is deprecated, and Ql makes no sense here.
• Replace a literal block with a list for the table of special names related to FD.
• Use Ql instead of ``X''.
• Add a dot after etc.
• Reference fuser(1).

MFC after: 1 week