Update USEFUL_TIPS.md

Author: valkyrienyanko

.github/USEFUL_TIPS.md

@@ -3,6 +3,8 @@
 ## Logging packet opcodes
 If you don't see the opcodes, these lines of code might be commented out. Feel free to un-comment them when debugging the netcode. 
 
+> ⚠️ Lobby packets have 2 opcodes, the first is the 'Lobby' opcode and the next is the lobby opcode type, e.g. 'LobbyJoin'. Perhaps this information should be logged too.
+
 ### Server packets
 https://github.com/GodotModules/GodotModulesCSharp/blob/4e1f6b20c99256a5ac2164b463412f64d87f942d/Scripts/Netcode/Server/GameServer.cs#L101-L103