Fix set greet message (command changes the wrong entry)

src/main/java/moe/sob/commands/SetGreetMessageCommand.java

@@ -13,7 +13,7 @@ public class SetGreetMessageCommand implements CommandExecutor {
         } else {
             try {
                 String greetMessage = String.join(" ", args);
-                Main.configR.set("server.greet_message", greetMessage);
+                Main.configR.set("server.entry_message", greetMessage);
                 Main.configR.save(Main.config);
 
                 sender.sendMessage("Changed greet message successfully.");