Doc: Fix spelling

Legned -> Legend
mainatined -> maintained

Legend is now Lenovo, so more fixes (text and url)
would be possible, too.

Cc: Jiri Kosina <trivial@kernel.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NStefan Weil <weil@mail.berlios.de>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Documentation/arm/SA1100/FreeBird

-Freebird-1.1 is produced by Legned(C) ,Inc.
+Freebird-1.1 is produced by Legend(C), Inc.
 http://web.archive.org/web/*/http://www.legend.com.cn
-and software/linux mainatined by Coventive(C),Inc.
+and software/linux maintained by Coventive(C), Inc.
 (http://www.coventive.com)
 
 Based on the Nicolas's strongarm kernel tree.