Clarify PolyScope X support
Throughout the docs we have marked PolyScope X support preliminary, e.g. here or here.
From my understanding, the ExternalControl URCapX is now in a state where we could remove the beta statements, would you agree @urrsk @urmahp?
I will say we need to have the External control for Polyscope X to support multiple external control nodes in one program before we can remove the beta flag
I wouldn't consider the URCap as under development any longer, so I would either delete the last comment or just write, that you would need a different URCap for PolyScopeX.
Do we consider to make any breaking changes to the URCap? Because if we are not I would consider removing the beta flag and then just list the features that isn't supported yet.