audio/qtractor: Add instructions to pkg-message

audio/qtractor/pkg-message

@@ -6,6 +6,9 @@ You installed Qtractor: an audio/MIDI multi-track sequencer application.
 
 In order to use it you need to install and run alsa-seq-server which
 creates /dev/snd/seq that is required by Qtractor.
+
+Please note that alsa-seq-server, in turn, needs this line in /boot/loader.conf:
+cuse4bsd_load="YES"
 ===============================================================================
 EOM
 }