tiger lee

a README.md to show how-to-use would be better

as I know, metadata in namesrv include kv config and topic route info that producers and consumers use for send and consume messages rely on. how producers use topic route...

fail to run example for `examples/consumer/highlevelpull/main.go` update like bellow would be OK.

> > fail to run example for `examples/consumer/highlevelpull/main.go` > > > > update like bellow would be OK. > > > > I have fixed this. nice!

- pls take PR to master - over 5k files changed. that maybe be a mistake. can you pull the lastest code and merge it , then re-produce this PR....

- pls take PR to master - over 5k files, there shoud be something wrong, you can pull the lastest code , and retry by another PR.

公司：VIPKID 地点：中国北京 联系方式： mail : [email protected] wechat: [email protected] 场景与规模：我们用了基于CPP的Python客户端，RocketMQ集群规模大约 30+台broker，10k+队列数，Python客户端规模100+个，主要用于支持公司核心业务，上线时间2019年8月。

just master for now. why u need collect slave ?

@celery-xqq an example for your consideration https://github.com/rocketmq-ps/rocketmq-exporter-docker

this PR should not be merged util RocketMQ 4.9.4 release: https://github.com/apache/rocketmq/releases