Docs for Reliable Messaging

[Jarno458]

No description provided.

[Jarno458]

Converted to draft as feedback came in discord and an other issue was found

[Th3Fanbus]

Said feedback in question: https://discord.com/channels/555424930502541343/1036634533077979146/1467634085265670196

Summarising the above:
We should avoid doing reliable messaging logic in a subsystem, because on more complicated cases than "send a single message on join" you might need to store additional data on a per-player-controller basis. In the current example, the subsystem hooks player controller begin play to send an initial message; one could instead send the message in BeginPlay of a mixin/actor component.

In contrast, vanilla does reliable messaging logic in a player controller component. Mods can do this in player controller mixins. Apparently one can make a C++ class derived from "UActorMixin" (or is it UBlueprintActorMixin?) to have custom C++ code in an actor mixin, but this still needs to be worked out.

[Jarno458]

This PR is back on menu boys!