add entry to ChangeLog
diff --git a/ChangeLog b/ChangeLog
index 07cc876..164092a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -9,6 +9,13 @@
    * Remove a duplicate #include in a sample program. Fixed by Masashi Honma #2326.
    * Reduce stack usage of `mpi_write_hlp()` by eliminating recursion.
      Fixes #2190.
+   * Server's RSA certificate in certs.c was SHA-1 signed. In the default
+     mbedTLS configuration only SHA-2 signed certificates are accepted.
+     This certificate is used in the demo server programs, which lead the
+     client programs to fail at the peer's certificate verification
+     due to an unacceptable hash signature. The certificate has been
+     updated to one that is SHA-256 signed. Fix contributed by
+     Illya Gerasymchuk.
 
 Changes
    * Include configuration file in all header files that use configuration,