COMPMID-1008: Fix Doxygen issues

Change-Id: Ie73d8771f85d1f5b059f3a56f1bbd73c98e94a38
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/124723
Reviewed-by: Michalis Spyrou <michalis.spyrou@arm.com>
Tested-by: Jenkins <bsgcomp@arm.com>
diff --git a/tests/framework/Exceptions.h b/tests/framework/Exceptions.h
index f35c350..687305b 100644
--- a/tests/framework/Exceptions.h
+++ b/tests/framework/Exceptions.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017 ARM Limited.
+ * Copyright (c) 2017-2018 ARM Limited.
  *
  * SPDX-License-Identifier: MIT
  *
@@ -94,6 +94,10 @@
      */
     LogLevel level() const;
 
+    /** Get the error message.
+     *
+     * @return error message.
+     */
     const char *what() const noexcept override;
 
 private: