diff --git a/doc/release-notes/upgrading.en.rst b/doc/release-notes/upgrading.en.rst
index 4dad49b117e..1ffd52255e8 100644
--- a/doc/release-notes/upgrading.en.rst
+++ b/doc/release-notes/upgrading.en.rst
@@ -56,6 +56,8 @@ The following APIs have changed, either in semantics, interfaces, or both.
 * Changed TS API
 
   * TSHttpTxnAborted
+  * TSMimeHdrPrint
+  * Enum values for hooks and events have been changed (ABI incompatible change)
 
 * Removed TS API
 
diff --git a/doc/release-notes/whats-new.en.rst b/doc/release-notes/whats-new.en.rst
index 2c9a55c1bd8..487cfdfb0a8 100644
--- a/doc/release-notes/whats-new.en.rst
+++ b/doc/release-notes/whats-new.en.rst
@@ -67,3 +67,9 @@ Symbols With INKUDP Prefix
 ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 In the plugin API, all types and functions starting with the prefix INKUDP are removed.
+
+New plugin hook for request sink transformation
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+A new hook, ``TS_HTTP_REQUEST_CLIENT_HOOK``, has been added. This provides the analoguas functionality of
+``TS_HTTP_RESPONSE_CLIENT_HOOK``, for request bodies.