[example] 对版权信息进行人工扫描并添加确实的版权信息

examples/ymodem/echo.c

@@ -1,3 +1,12 @@
+/*
+ * Copyright (c) 2006-2021, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ */
+
 #include <ymodem.h>
 
 static rt_device_t _odev;

examples/ymodem/null.c

@@ -1,3 +1,12 @@
+/*
+ * Copyright (c) 2006-2021, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ */
+
 #include <ymodem.h>
 
 static enum rym_code _rym_dummy_write(

examples/ymodem/tofile.c

@@ -1,3 +1,12 @@
+/*
+ * Copyright (c) 2006-2021, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ */
+
 #include <rtthread.h>
 #include <ymodem.h>
 #include <dfs_posix.h>