[konheko] Fix application launch via desktop file when already running in background

It looks a bit ugly now, but at least you can launch it again! Maybe we
can fix it properly by making the app properly launch via dbus?

harbour-konheko.desktop

@@ -3,6 +3,7 @@ Type=Application
 Icon=harbour-konheko
 Exec=harbour-konheko
 X-Nemo-Application-Type=silica-qt5
+X-Nemo-Single-Instance=no
 Name=Konheko
 Categories=Chat;Network
 # translation example: