Clarify StationUUID description

[petrvanekrobe]

UUID for the station inside the network.

Remove the second sentence about persistence.

[Verschwiegener]

Should the StationUUID not be persistent?

[petrvanekrobe]

Should the StationUUID not be persistent?

Having StationUUID persistence is not strictly required at this point but is very useful especially to build further features on top of the protocol in the future. We are looking for better way to describe it as there were different interpretations of what "persistent" means.