Add translations for statement-based searches in main frontend

frontend/tl/navigation.json

@@ -17,6 +17,7 @@
         "articles": "Artikulo",
         "events": "Mga kaganapan",
         "select_language": "Pumili ng wika",
-        "join_us": "Makilahok!"
+        "join_us": "Makilahok!",
+        "browse_backgrounds": "Browse \"background information\""
     }
 }