Add chart ver and communication badges
:target: https://binderhub.readthedocs.io/en/latest/?badge=latest
:alt: Documentation Status
+.. image:: https://img.shields.io/badge/dynamic/json.svg?label=latest&url=https://jupyterhub.github.io/helm-chart/info.json&query=$.binderhub.latest&colorB=orange
+ :target: https://jupyterhub.github.io/helm-chart/
+ :alt: Latest chart development release
+
+.. image:: https://img.shields.io/badge/issue_tracking-github-blue.svg
+ :target: https://github.com/jupyterhub/binderhub/issues
+ :alt: GitHub
+
+.. image:: https://img.shields.io/badge/help_forum-discourse-blue.svg
+ :target: https://discourse.jupyter.org/c/binder/binderhub
+ :alt: Discourse
+
+.. image:: https://img.shields.io/badge/social_chat-gitter-blue.svg
+ :target: https://gitter.im/jupyterhub/binder
+ :alt: Gitter
+
What is BinderHub?
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