Update en.json (#3907)

Fixed grammar for e-mail notfication changing sign-in method

i18n/en.json

@@ -1737,7 +1737,7 @@
   },
   {
     "id": "api.templates.singin_change_email.body.info",
-    "translation": "You updated your sign-in method for on {{ .SiteName }} to {{.Method}}.<br>If this change wasn't initiated by you, please contact your system administrator."
+    "translation": "You updated your sign-in method on {{ .SiteName }} to {{.Method}}.<br>If this change wasn't initiated by you, please contact your system administrator."
   },
   {
     "id": "api.templates.singin_change_email.subject",