Add credits to ChangeLog
diff --git a/ChangeLog b/ChangeLog
index 744cb68..def6891 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,7 +3,8 @@
 = mbed TLS 2.2.1 released 2015-12-xx
 
 Security
-   * Disable MD5 for handshake signatures by default.
+   * Disable MD5 handshake signatures in TLS 1.2 by default
+     (Reported by Karthikeyan Bhargavan and Gaëtan Leurent.)
 
 = mbed TLS 2.2.0 released 2015-11-04