Add JoinTown to powered-by list (#2078)

* Update powered-by.md

* Update powered-by.md

I change the order. This list should be in alphabeta order.

docs/powered-by.md

@@ -31,6 +31,7 @@ or providing commercial products including Apache SkyWalking.
 1. iFLYTEK. 科大讯飞股份有限公司-消费者BG http://www.iflytek.com/
 1. Ke.com. 贝壳找房. https://www.ke.com
 1. Keking.cn 凯京集团. http://www.keking.cn
+1. JoinTown. 九州通医药集团 http://www.jztey.com/
 1. Lagou.com. 拉勾. https://www.lagou.com/
 1. laocaibao. 上海证大爱特金融信息服务有限公司 https://www.laocaibao.com/
 1. Lima 北京力码科技有限公司 https://www.zhongbaounion.com/
@@ -57,7 +58,6 @@ or providing commercial products including Apache SkyWalking.
 1. Yinji(shenzhen)Network Technology Co.,Ltd. 印记. http://www.yinjiyun.cn/
 1. Yonghui Superstores Co., Ltd. 永辉超市 http://www.yonghui.com.cn
 
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 # User Cases
 ## ke.com
 ### Deployment Configuration