MAINTAINERS: update list of Oxnas maintainers

Add a new list address in the MAINTAINERS file for the Oxnas platform.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

MAINTAINERS

@@ -1443,6 +1443,7 @@ F:	arch/arm/mach-orion5x/ts78xx-*
 ARM/OXNAS platform support
 M:	Neil Armstrong <narmstrong@baylibre.com>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
+L:	linux-oxnas@lists.tuxfamily.org (moderated for non-subscribers)
 S:	Maintained
 F:	arch/arm/mach-oxnas/
 F:	arch/arm/boot/dts/oxnas*