Add missing string

Author: andi34

resources/lang/en.json

@@ -185,6 +185,7 @@
   "manual_randomPicture": "If enabled, random pictures will be shown at standalone gallery.",
   "manual_remove_config": "If enabled, personal config gets removed on reset.",
   "manual_remove_images": "If enabled, all images gets removed on reset.",
+  "manual_remove_mailtxt": "If enabled, mail database gets removed on reset.",
   "manual_rounded_corners": "If enabled, the Photobooth UI uses smooth rounded edges.",
   "manual_scrollbar": "If enabled, a scrollbar is visible in gallery.",
   "manual_send_all_later": "If enabled, entered email adresses get stored inside a database instead sending choosed picture directly. For example, this can be used to send a mail with all pictures or a link to an online gallery after the event.",