Update output message when certification verified fail


Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/programs/ssl/ssl_client2.c b/programs/ssl/ssl_client2.c
index d183c66..11c3ccc 100644
--- a/programs/ssl/ssl_client2.c
+++ b/programs/ssl/ssl_client2.c
@@ -2240,7 +2240,10 @@
                     "    or you didn't set ca_file or ca_path "
                         "to an appropriate value.\n"
                     "    Alternatively, you may want to use "
-                        "auth_mode=optional for testing purposes.\n" );
+                        "auth_mode=optional for testing purposes if "
+                        "server is not TLS 1.3.\n"
+                    "    For TLS 1.3 server, try `ca_path=/etc/ssl/certs/`"
+                        "or other folder that has root certificates\n" );
             mbedtls_printf( "\n" );
             goto exit;
         }