[arch-mirrors] mirror.sandyriver.net changes

Storage array upgrades has been completed to mirror.sandyriver.net http://mirror.sandyriver.net/ mirror.sandyriver.net now points to mirror2.sandyriver.net http://mirror2.sandyriver.net/ as the system has been moved to new hardware please update links to mirror2.sandyriver.net http://mirror2.sandyriver.net/ to ensure no issues. Thanks