Merge pull request #780 from pouchrobot/auto-doc-2019-08-03

docs: auto generate Dragonfly cli/api/contributors docs via code

Author: allencloud

CONTRIBUTORS

@@ -31,6 +31,7 @@ KevinBetterQ <1093850932@qq.com>
 leiiwang <u2takey@gmail.com>
 liuheng <liuhengloveyou@gmail.com>
 liuyuxing <31209634+Starnop@users.noreply.github.com>
+longfei.shang@daocloud.io <longf_shang@163.com>
 lowzj <zj3142063@gmail.com>
 lurenjia528 <37833630+lurenjia528@users.noreply.github.com>
 pouchrobot <pouch-dev@list.alibaba-inc.com>