It should be Documentation/build/kconfig.txt.

Introduced by commit 2af238e4


("kbuild: make *config usage docs").

Signed-off-by: Li Zefan <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>