kconfig.debug: clarify CONFIG_DEBUG_INFO help text

The following patch adds some extra clarification to the CONFIG_DEBUG_INFO
Kconfig help text.  The current text is mostly a recursive definition and
doesn't really say much of anything.  When I first read this I thought it
was going to enable extra verbosity in debug messages or something, but it
is only enabling the "gcc -g" compile option in the Makefile.
Signed-off-by: NAndreas Dilger <adilger@clusterfs.com>
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>

lib/Kconfig.debug

@@ -333,6 +333,9 @@ config DEBUG_INFO
 	help
           If you say Y here the resulting kernel image will include
 	  debugging info resulting in a larger kernel image.
+	  This adds debug symbols to the kernel and modules (gcc -g), and
+	  is needed if you intend to use kernel crashdump or binary object
+	  tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 	  Say Y here only if you plan to debug the kernel.
 
 	  If unsure, say N.