Change email group name , add twitter icon (apache#999)

Author: lovepoem

CODE_OF_CONDUCT.md

@@ -55,7 +55,7 @@ further defined and clarified by project maintainers.
 ## Enforcement
 
 Instances of abusive, harassing, or otherwise unacceptable behavior may be
-reported by contacting the project team at dev.fescar@gmail.com. All
+reported by contacting the project team at dev-seata@googlegroups.com. All
 complaints will be reviewed and investigated and will result in a response that
 is deemed necessary and appropriate to the circumstances. The project team is
 obligated to maintain confidentiality with regard to the reporter of an incident.

README.md

@@ -6,6 +6,7 @@
 [![codecov](https://codecov.io/gh/seata/seata/branch/develop/graph/badge.svg)](https://codecov.io/gh/seata/seata)
 [![license](https://img.shields.io/github/license/seata/seata.svg)](https://www.apache.org/licenses/LICENSE-2.0.html)
 [![maven](https://img.shields.io/maven-central/v/io.seata/seata-parent.svg)](https://search.maven.org/search?q=io.seata)
+[![](https://img.shields.io/twitter/follow/seataio.svg?label=Follow&style=social&logoWidth=0)](https://twitter.com/intent/follow?screen_name=seataio)
 
 ## What is Seata?
 
@@ -126,7 +127,7 @@ Contributors are welcomed to join the FEATS project. Please check [CONTRIBUTING]
 * [Twitter](https://twitter.com/seataio): Follow along for latest Seata news on Twitter.
 
 * Mailing list: 
-  * dev-fescar@googlegroups.com , for dev/user discussion. [subscribe](mailto:dev-fescar[email protected]), [unsubscribe](mailto:dev-fescar[email protected]), [archive](https://groups.google.com/forum/#!forum/dev-fescar)
+  * dev-seata@googlegroups.com , for dev/user discussion. [subscribe](mailto:dev-seata[email protected]), [unsubscribe](mailto:dev-seata[email protected]), [archive](https://groups.google.com/forum/#!forum/dev-seata)
 
 **Dingtalk**