[recipes] Mark missing string for translation

[Piotr Drąg <piotrdrag src gnome org>]

commit 76bfc2f4bf3090cde83d7a880c5cc20ebe7d50d6
Author: Piotr Drąg <piotrdrag gmail com>
Date:   Fri Oct 27 20:09:20 2017 +0200

    Mark missing string for translation

 src/shopping-list-exporter-dialog.ui |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/shopping-list-exporter-dialog.ui b/src/shopping-list-exporter-dialog.ui
index efc86ed..1f8637f 100644
--- a/src/shopping-list-exporter-dialog.ui
+++ b/src/shopping-list-exporter-dialog.ui
@@ -149,7 +149,7 @@
                   </child>
                   <child>
                     <object class="GtkLinkButton" id="add_service">
-                      <property name="label">Add service</property>
+                      <property name="label" translatable="yes">Add service</property>
                        <property name="visible">1</property>
                        <property name="use_underline">0</property>
                        <property name="uri">switch</property>