Update ChangeLog with dtls sample IPv6 change
diff --git a/ChangeLog b/ChangeLog
index 8c82d08..27b7ca0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -13,6 +13,8 @@
* 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.
+ * Change the dtls_client and dtls_server samples to work by default over
+ IPv6 and optionally by a build option over IPv4.
= mbed TLS 2.1.15 branch released 2018-08-31