feat(example): Use CC0 license for examples

examples/protocols/openssl_server/main/user_main.c

@@ -1,26 +1,11 @@
-/*
- * ESPRESSIF MIT License
- *
- * Copyright (c) 2017 <ESPRESSIF SYSTEMS (SHANGHAI) PTE LTD>
- *
- * Permission is hereby granted for use on ESPRESSIF SYSTEMS ESP8266 only, in which case,
- * it is free of charge, to any person obtaining a copy of this software and associated
- * documentation files (the "Software"), to deal in the Software without restriction, including
- * without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
- * and/or sell copies of the Software, and to permit persons to whom the Software is furnished
- * to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in all copies or
- * substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
- * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
- * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
- * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
- * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- *
- */
+/* openSSL server example
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
 
 
 #include "esp_common.h"