buildroot

Trivial documentation fix for Signed-off-by

Make consistent the capitalization and punctuation of Signed-of-by examples.

Signed-off-by: Ralph Siemsen <ralphs@netwinder.org>
Acked-by: "Samuel Martin" <s.martin49@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>