Fixed Dutch translation (#544)

locales/nl.json

@@ -42,7 +42,7 @@
   "Welcome back! You've successfully signed in.": "Welkom terug! Je bent succesvol ingelogd.",
   "You've successfully subscribed to": "Je hebt je ingeschreven voor",
   "Your email address": "Je e-mailadres",
-  "of": "of",
+  "of": "van",
   "with the email address": "met het e-mailadres",
   "with this tag": "met deze tag"
 }