Commit missing translations

aleksis/core/assets/messages.json

 {
   "en": {
     "notifications": {
+      "notifications": "Notifications",
       "more_information": "More information",
       "no_notifications": "No notifications available yet.",
       "mark_as_read": "Mark as read"
@@ -40,6 +41,7 @@
   },
   "de": {
     "notifications": {
+      "notifications": "Benachrichtigungen",
       "more_information": "Mehr Informationen",
       "no_notifications": "Keine Benachrichtigungen verfügbar.",
       "mark_as_read": "Als gelesen markieren"