Fix typos in Documentation/: 'S'

This patch fixes typos in various Documentation txts. The patch addresses
some words starting with the letter 'S'.

Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com>
Acked-by: Alan Cox <alan@redhat.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Adrian Bunk <bunk@stusta.de>