README.kconfig: fix typo

Fix typo in defconfig file format description.

Signed-off-by: Igor Grinberg <grinberg@compulab.co.il>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
1 file changed