message: doc: Fix copyright years
diff: @@ -135,7 +135,7 @@ based, or message-passing via protobuf protocols.
  Buttplug is BSD licensed.
  - Copyright (c) 2019, Nonpolynomial Labs, LLC
  + Copyright (c) 2016-2019, Nonpolynomial Labs, LLC
  All rights reserved.
  Redistribution and use in source and binary forms, with or without
  