[Feature Request] Add file structure for Unreal client guide

[SnappierSoap318]

Add a file structure to the unreal client guide so that new users will know where to write the client side code.

from my expirence, i wrote all the code( authentication, add to matchmaking, and joinmatch) in the game instance class as i need the session to persist across levels.

[docsncode]

Hi, structuring your game is out of the scope of using Nakama's features. I can recommend looking at some Unreal specific guides for organizing/structuring your game and code.