Cleanup summary comments in ExtraTests

tests/ExtraTests/X90-WindowsHeaderInclusion.cpp

@@ -6,10 +6,12 @@
 
 // SPDX-License-Identifier: BSL-1.0
 
-// X90-WindowsHeaderInclusion.cpp
-// Test that the Catch2 header compiles even after including windows.h
-// without defining NOMINMAX first. As an FYI, if you do that, you are
-// wrong.
+/**\file
+ * Test that the Catch2 header compiles even after including windows.h
+ * without defining NOMINMAX first.
+ *
+ * As an FYI, if you do that, you are wrong.
+ */
 
 #include <windows.h>
 #include <catch2/catch_test_macros.hpp>