Fix example to actually be an echo bot (#125)

Author: surajkumar

example/echo-bot/src/main/java/com/javadiscord/jdi/example/EchoHandler.java

@@ -3,13 +3,18 @@
 import com.javadiscord.jdi.core.Guild;
 import com.javadiscord.jdi.core.annotations.EventListener;
 import com.javadiscord.jdi.core.annotations.MessageCreate;
+import com.javadiscord.jdi.core.api.builders.CreateMessageBuilder;
 import com.javadiscord.jdi.core.models.message.Message;
 
 @EventListener
 public class EchoHandler {
 
     @MessageCreate
     public void echoMessages(Message message, Guild guild) {
-        System.out.println("EchoHandler");
+        if (!message.author().bot()) {
+            guild.channel().createMessage(
+                new CreateMessageBuilder(message.channelId()).content(message.content())
+            );
+        }
     }
 }

example/echo-bot/src/main/java/com/javadiscord/jdi/example/ExampleNoAnnotate.java

@@ -4,8 +4,7 @@
 
 public class Main {
     public static void main(String[] args) {
-        Discord discord = new Discord("");
-        discord.registerListener(new ExampleNoAnnotate());
+        Discord discord = new Discord(System.getenv("BOT_TOKEN"));
         discord.start();
     }
 }