Add ChangeLog entry
diff --git a/ChangeLog b/ChangeLog
index e7abd5c..38704bc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -15,6 +15,7 @@
    * Fix leap year calculation in x509_date_is_valid() to ensure that invalid
      dates on leap years with 100 and 400 intervals are handled correctly. Found
      by Nicholas Wilson. #694
+   * Fix error message in programs/pkey/gen_key.c. Found and fixed by Chris Xue.
 
 = mbed TLS 2.6.0 branch released 2017-08-10