Updated Debug mode (markdown)

Debug-mode.md

@@ -2,7 +2,7 @@ When something isn't working as expected, it might be useful to take a peek "und
 
 ## Enabling debug
 
-To enable debug, you can go to the [BuildOpt.h](https://github.com/jgromes/RadioLib/blob/master/src/BuildOpt.h) file, and uncomment either one or both of these lines:
+To enable debug, you can go to the [BuildOptUser.h](https://github.com/jgromes/RadioLib/blob/master/src/BuildOptUser.h) file, and uncomment either one or both of these lines:
 
 ```c++
 //#define RADIOLIB_DEBUG