todo in whats new

Author: rustagir

source/whats-new.txt

@@ -120,10 +120,9 @@ Improvements in 5.1
 New Features in 5.1
 ~~~~~~~~~~~~~~~~~~~
 
-- Support for polymorphic serialization.
-
-.. TODO: Add link to Kotlin Serialization page when ready: https://jira.mongodb.org/browse/DOCSP-42666 . 
-.. ex. To learn more, see the :ref:`kotlin-sync-polymorphic` section of the Kotlin Sync Serialization guide.
+- Support for polymorphic serialization. To learn more, see the
+  :ref:`kotlin-sync-polymorphic` section of the Kotlin Sync
+  Serialization guide.
 
 - Introduces the ``serverMonitoringMode`` connection URI option. To
   learn more, see the :ref:`kotlin-sync-connection-options` guide.