It should be Documentation/build/kconfig.txt.
Introduced by commit 
2af238e455ef5fd31c2f7a06c2db3f13d843b9bf
("kbuild: make *config usage docs").
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
                           values to random values.
 
    You can find more information on using the Linux kernel config tools
-   in Documentation/kbuild/make-configs.txt.
+   in Documentation/kbuild/kconfig.txt.
 
        NOTES on "make config":
        - having unnecessary drivers will make the kernel bigger, and can