UX: clarify setting with description (#40)

Author: awesomerobot

locales/en.yml

@@ -26,4 +26,5 @@ en:
               description: The URL to link to
             target:
               label: Target
-              description: The target attribute for the link
+              description: The target attribute for the link
+      show_bar_on_mobile: When enabled, the desktop version of the header bar will be displayed on mobile devices