Update Lobby Bot README.
Reviewed By: Itms
Differential Revision: https://code.wildfiregames.com/D79
Nobody cares about outdated versions shipped with soon to be unsupported versions of distros.
Also when making the install instructions incomplete one could remove copy pasta install instructions completely given that they differ based on the used package manager.
Could have used # apt install ..., here and in a few other places.
Why did we switch this file to use markdown if nobody bothers to actually use it?