doc: Fix typo "is is" in Documentations

Fix double words "is is" in Documentations.

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Rob Landley <rob@landley.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
5 files changed