Added changelog entry

ChangeLog

diff --git a/ChangeLog b/ChangeLog
index 13de867..dd571f9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 mbed TLS ChangeLog (Sorted per branch, date)
 
+= mbed TLS 2.x.x branch released xxxx-xx-xx
+
+Changes
+   * Send fatal alerts in many more cases instead of dropping the connection.
+
 = mbed TLS 2.4.2 branch released 2017-03-08
 
 Security