minor fix _get_charge_line

booking.py

@@ -630,7 +630,7 @@ class Booking(Workflow, ModelSQL, ModelView):
     def _get_charge_line(cls, cha, bk):
         description = cha.product.template.name
         if cha.order:
-            description.append(cha.order)
+            description = cha.description + ' | ' + cha.order
         if cha.kind == 'accommodation':
             description = cha.description + ' | ' + str(cha.date_service)