better comment description for mrbconf.h configuration

include/mrbconf.h

@@ -43,16 +43,15 @@
 /* page size of memory pool */
 //#define POOL_PAGE_SIZE 16000
 
-/* -DDISABLE_XXXX to drop the feature */
+/* -DDISABLE_XXXX to drop following features */
 //#define DISABLE_SPRINTF	/* Kernel.sprintf method */
 //#define DISABLE_MATH		/* Math functions */
 //#define DISABLE_TIME		/* Time class */
 //#define DISABLE_STRUCT	/* Struct class */
 //#define DISABLE_STDIO		/* use of stdio */
-//#define ENABLE_DEBUG    /* hooks for debugger */
 
-/* Now DISABLE_GEMS is added as a command line flag in Rakefile, */
-/* we do not need to set it here. */
+/* -DENABLE_XXXX to enable following features */
+//#define ENABLE_DEBUG		/* hooks for debugger */
 
 /* end of configuration */