docs: add docs

src/main/java/com/lapisberry/net/Server.java

@@ -66,6 +66,7 @@ public void processPacketFromClient(ClientHandler sender, ClientPacket packet) {
         System.out.println("Processing packet from " + sender.getSocket().getInetAddress().getHostAddress() + ": " + packet);
         if (packet instanceof JoinRequestPacket joinRequestPacket) {
             serverLobby.addPlayer(sender.getClientId(), joinRequestPacket.getUsername());
+            // Have to make a copy of the players list to avoid shared reference
             ArrayList<Pair<Integer, String>> players = new ArrayList<>(serverLobby.getPlayers());
             sendPacketToAllClients(new LobbyPacket(players));
         }
@@ -82,6 +83,7 @@ public void close() {
     public void removeClientHandler(ClientHandler clientHandler) {
         clientHandlers.remove(clientHandler);
         serverLobby.removePlayer(clientHandler.getClientId());
+        // Have to make a copy of the players list to avoid shared reference
         ArrayList<Pair<Integer, String>> players = new ArrayList<>(serverLobby.getPlayers());
         sendPacketToAllClients(new LobbyPacket(players));
     }

src/main/java/com/lapisberry/net/packets/JoinResponsePacket.java

@@ -3,6 +3,9 @@
 import java.io.Serial;
 import java.io.Serializable;
 
+/**
+ * The {@code JoinResponsePacket} class is the packet sending from server to client to response the {@code JoinRequestPacket}.
+ */
 public class JoinResponsePacket extends ServerPacket implements Serializable {
     @Serial
     private static final long serialVersionUID = -5576292645379280835L;