luci-base: add robots.txt
luci-base: add robots.txt

There is no reason to have LuCI crawled by default.

Signed-off-by: Oliver Middleton <eb57605890ead666b3f42952314868032ae8a429@gmail.com>

ollie27/openwrt_luci,ollie27/openwrt_luci,ollie27/openwrt_luci,ollie27/openwrt_luci,ollie27/openwrt_luci,ollie27/openwrt_luci,ollie27/openwrt_luci,ollie27/openwrt_luci