message: doc: Updated message flow
  Made message flow directions clearer
diff: @@ -467,13 +467,14 @@ There are two types of message flows.
  - Messages can be sent from the server/library to a client. Messages
  like DeviceAdded, DeviceRemoved, and certain device specific input
  - messages can happen without the client making a request.
  + messages can happen without the client making a request. The server
  + will not expect a reply from the client for these messages.
  - Messages sent from the client to the server will always receive a
  - reply. The message type the client will receive in reply is based on
  - the type of message sent. Some messages may receive a simple "Ok"
  - message in reply in order to denote successful receiving, while
  - others may receive something context specific. Messages reply types
  - are listed in the message descriptions section.
  + reply from the server. The message type the client will receive in
  + reply is based on the type of message sent. Some messages may
  + receive a simple "Ok" message in reply in order to denote successful
  + receiving, while others may receive something context specific.
  + Messages reply types are listed in the message descriptions section.
  *** A Note On Scaling
  