doc: add small changes && fix some bug (#261)

diff --git a/README.md b/README.md
index be0f0b5..2158823 100644
--- a/README.md
+++ b/README.md
@@ -72,8 +72,11 @@
 - http://apache.org/foundation/mailinglists.html#subscribing
 
 ### Contact Us
-- [Github Issues](https://github.com/apache/incubator-hugegraph/issues): Feedback on usage issues and functional requirements (priority)
-- Feedback Email: [dev@hugegraph.apache.org](mailto:dev@hugegraph.apache.org)
-- WeChat public account: Apache HugeGraph, welcome to scan this QR code to follow us.
 
-<img src="./assets/images/wechat.png">
+---
+
+ - [GitHub Issues](https://github.com/apache/incubator-hugegraph-doc/issues): Feedback on usage issues and functional requirements (quick response)
+ - Feedback Email: [dev@hugegraph.apache.org](mailto:dev@hugegraph.apache.org) ([subscriber](https://hugegraph.apache.org/docs/contribution-guidelines/subscribe/) only)
+ - WeChat public account: Apache HugeGraph, welcome to scan this QR code to follow us.
+
+ <img src="./assets/images/wechat.png" alt="QR png" width="350"/>