Fix spelling mistake (#12817)

config/locales/en.yml

@@ -339,7 +339,7 @@ en:
       delete: Delete
       destroyed_msg: Successfully deleted e-mail domain from blacklist
       domain: Domain
-      empty: No e-mail domains currenly blacklisted.
+      empty: No e-mail domains currently blacklisted.
       new:
         create: Add domain
         title: New e-mail blacklist entry