Shorted WorkstationOstree in volume ID

Since this is basically a workaround, it should look like it was part of
regular Workstation.

Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

fedora.conf

@@ -247,6 +247,7 @@ volume_id_substitutions = {
      'Design_suite': 'Dsgn',
             'Games': 'Game',
           'Jam_KDE': 'Jam',
+'WorkstationOstree': 'WS',
       'Workstation': 'WS',
        'Everything': 'E',
            'Server': 'S',