Kbuild/doc: fix links to Documentation files

Fix links to files in Documentation/* in various Kconfig files

Signed-off-by: Dirk Hohndel <hohndel@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index d7a600a..21a9fcc 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -363,7 +363,7 @@
 	  the tables, chains, rules.
 
 	  If you want to compile it as a module, say M here and read
-	  <file:Documentation/modules.txt>.  If unsure, say `N'.
+	  <file:Documentation/kbuild/modules.txt>.  If unsure, say `N'.
 
 config NETFILTER_XT_TARGET_SECMARK
 	tristate '"SECMARK" target support'