Improve documentation of game messages

[Garanas]

Related to: FAForever/fa#6479

Improves the documentation of some of the game messages.

[Askaholic]

Cool, thanks! I hope to find some time this weekend to implement the established peers.

What are we expecting the server to do with the launch status information? If we’re just ignoring most of it you could also just add the possible options in the docstring and get rid of the empty if chain.

[Garanas]

The launch status can help you understand what is happening to a player/connection. For example - a player that has the status Ready is connected to all its peers and is ready to launch. Such a player should never receive a (time) penalty if the lobby does not start for some reason.

edit: perhaps 'launch status' is the wrong term to use here.

[Askaholic]

I'm just going to combine this with #1028 for simplicity. Thanks for making the initial changes!