bgpwtf/invoice: format for non-eu customers

Change-Id: I42ec23d911cd69a310a6de8ffe5dca5ff1b30f00
diff --git a/bgpwtf/invoice/render.go b/bgpwtf/invoice/render.go
index c0eeca1..db5c151 100644
--- a/bgpwtf/invoice/render.go
+++ b/bgpwtf/invoice/render.go
@@ -53,7 +53,11 @@
 	if len(parts) > 0 {
 		symbols = strings.Join(parts, ", ") + "."
 	} else {
-		symbols = "<i>brak</i>."
+		if language == "en" {
+			symbols = "<i>brak (none)</i>."
+		} else {
+			symbols = "<i>brak</i>."
+		}
 	}
 
 	data := struct {