Fix mdns_lite hosts warning

Author: fhunleth

config/target.exs

@@ -38,7 +38,7 @@ config :mdns_lite,
   # "nerves.local" for convenience. If more than one Nerves device is on the
   # network, delete "nerves" from the list.
 
-  host: [:hostname, "nerves"],
+  hosts: [:hostname, "nerves"],
   ttl: 120,
 
   # Advertise the following services over mDNS.