base64: separate license and brief of file for visibility

common/base64.c

@@ -1,7 +1,5 @@
 /**
- * xrdp: A Remote Desktop Protocol server.
- *
- * Copyright (C) Koichiro Iwao 2017
+ * Copyright (C) 2017 Koichiro Iwao, all xrdp contributors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,7 +13,11 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
- * Base64 encoder / decoder
+ */
+
+/**
+ * @file    common/base64.c
+ * @brief   Base64 encoder / decoder
  */
 
 #if defined(HAVE_CONFIG_H)