Various fixes to doxygen API generation

 * Fixed incorrect file definitions
 * Corrected function naming in X.509 module definition
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 68153ef..8a848fe 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -3,6 +3,10 @@
  *
  * \brief Configuration options (set of defines)
  *
+ *  This set of compile-time options may be used to enable
+ *  or disable features selectively, and reduce the global
+ *  memory footprint.
+ *
  *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
  *  SPDX-License-Identifier: Apache-2.0
  *
@@ -21,11 +25,6 @@
  *  This file is part of mbed TLS (https://tls.mbed.org)
  */
 
-/*
- * This set of compile-time options may be used to enable
- * or disable features selectively, and reduce the global
- * memory footprint.
- */
 #ifndef MBEDTLS_CONFIG_H
 #define MBEDTLS_CONFIG_H