add note (#3550)

connector/rocketmq-connector/src/main/java/com/alibaba/otter/canal/connector/rocketmq/producer/CanalRocketMQProducer.java

@@ -331,6 +331,7 @@ public class CanalRocketMQProducer extends AbstractMQProducer implements CanalMQ
                 }
 
                 try {
+                    // 阿里云RocketMQ暂不支持批量发送消息，当canal.mq.flatMessage = true时，会发送失败
                     SendResult sendResult = this.defaultMQProducer.send(messages, queue);
                     if (logger.isDebugEnabled()) {
                         logger.debug("Send Message Result: {}", sendResult);

example/src/main/java/com/alibaba/otter/canal/example/rocketmq/CanalRocketMQClientExample.java

@@ -9,7 +9,7 @@ import org.slf4j.LoggerFactory;
 import org.springframework.util.Assert;
 
 /**
- * Kafka client example
+ * RocketMQ client example
  *
  * @author machengyuan @ 2018-6-12
  * @version 1.0.0

example/src/main/java/com/alibaba/otter/canal/example/rocketmq/CanalRocketMQClientFlatMessageExample.java

@@ -11,7 +11,7 @@ import com.alibaba.otter.canal.client.rocketmq.RocketMQCanalConnector;
 import com.alibaba.otter.canal.protocol.FlatMessage;
 
 /**
- * Kafka client example
+ * RocketMQ client example
  *
  * @author machengyuan @ 2018-6-12
  * @version 1.0.0