Merge pull request #5600 from Rageking8/update-debug-macro-reference

Update `_DEBUG` macro reference

Author: v-dirichards

docs/c-runtime-library/debug.md

@@ -1,16 +1,16 @@
 ---
-description: "Learn more about: _DEBUG"
 title: "_DEBUG"
-ms.date: "11/04/2016"
+description: "Learn more about: _DEBUG"
+ms.date: 11/04/2016
 helpviewer_keywords: ["DEBUG macro", "_DEBUG macro"]
-ms.assetid: a9901568-4846-4731-a404-399d947e2e7a
 ---
 # `_DEBUG`
 
-The compiler defines `_DEBUG` when you specify the /MTd or /MDd option. These options specify debug versions of the C run-time library.
+The compiler defines `_DEBUG` when you specify the [`/MTd`](../build/reference/md-mt-ld-use-run-time-library.md), [`/MDd`](../build/reference/md-mt-ld-use-run-time-library.md), or [`/LDd`](../build/reference/md-mt-ld-use-run-time-library.md) option. These options specify debug versions of the C run-time library.
 
-For more information, see [CRT debugging techniques](./crt-debugging-techniques.md).
+For more information, see [CRT debugging techniques](crt-debugging-techniques.md).
 
 ## See also
 
-[Control flags](./control-flags.md)
+[Control flags](control-flags.md)\
+[Predefined macros](../preprocessor/predefined-macros.md)