Ticket #48290 - No man page entry for - option '-u' of dbgen.pl for adding group entries with uniquemembers
    
    Description: Adding a missing option to the man page for dbgen.pl.
      -u  Add groups containing uniquemembers; generate a group for every
          100 user entries created that contains the 100 members
    
    https://fedorahosted.org/389/ticket/48290
    
    Reviewed by mreynolds@redhat.com (Thank you, Mark!!)