Update README.md

Author: mariobehling

README.md

@@ -8,6 +8,8 @@
 [![Codecov branch](https://codecov.io/gh/fossasia/open-event-server/branch/master/graph/badge.svg?style=flat-square)](https://codecov.io/gh/fossasia/open-event-server)
 [![Gitter](https://img.shields.io/badge/chat-on%20gitter-ff006f.svg?style=flat-square)](https://gitter.im/fossasia/open-event-server)
 [![Reviewed by Hound](https://img.shields.io/badge/Reviewed_by-Hound-8E64B0.svg)](https://houndci.com)
+[![Mailing List](https://img.shields.io/badge/Mailing%20List-FOSSASIA-blue.svg)](https://groups.google.com/forum/#!forum/open-event)
+[![Twitter Follow](https://img.shields.io/twitter/follow/eventyay.svg?style=social&label=Follow&maxAge=2592000?style=flat-square)](https://twitter.com/eventyay)
 
 > **The Open Event Server enables organizers to manage events from concerts to conferences and meet-ups.**