Add follow-up issue url for @todo - #3425141.

core/modules/datetime_range/src/DateTimeRangeConstantsInterface.php

@@ -4,7 +4,9 @@
 
 /**
  * Declares constants used in the datetime range module.
+ *
  * @todo Convert this to an enum in 11.0.
+ * @see https://www.drupal.org/project/drupal/issues/3425141.
  */
 interface DateTimeRangeConstantsInterface {