Add ChangeLog entry
diff --git a/ChangeLog b/ChangeLog
index 027a971..8c2d90d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 mbed TLS ChangeLog (Sorted per branch, date)
 
+= mbed TLS 2.xx.xx branch released xxxx-xx-xx
+
+Changes
+   * Close a test gap in (D)TLS between the client side and the server side:
+     test the handling of large packets and small packets on the client side
+     in the same way as on the server side.
+
 = mbed TLS 2.11.0 branch released 2018-06-18
 
 Features