Add various README badges

Author: consideRatio

README.md

@@ -5,6 +5,13 @@
 
 ![Code Cov](https://img.shields.io/codecov/c/github/jupyterhub/nativeauthenticator.svg)
 
+[![Documentation build status](https://img.shields.io/readthedocs/native-authenticator?logo=read-the-docs&logoColor=white)](https://native-authenticator.readthedocs.org/en/latest/)
+[![Latest PyPI version](https://img.shields.io/pypi/v/jupyterhub-nativeauthenticator?logo=pypi&logoColor=white)](https://pypi.python.org/pypi/jupyterhub-nativeauthenticator)
+<br>
+[![GitHub](https://img.shields.io/badge/issue_tracking-github-blue?logo=github)](https://github.com/jupyterhub/jupyterhub/issues)
+[![Discourse](https://img.shields.io/badge/help_forum-discourse-blue?logo=discourse)](https://discourse.jupyter.org/c/jupyterhub)
+[![Gitter](https://img.shields.io/badge/social_chat-gitter-blue?logo=gitter)](https://gitter.im/jupyterhub/jupyterhub)
+[![Contribute](https://img.shields.io/badge/I_want_to_contribute!-grey?logo=jupyter)](https://github.com/jupyterhub/nativeauthenticator/blob/master/CONTRIBUTING.md)
 
 A simple authenticator for small-medium size [JupyterHub](http://github.com/jupyter/jupyterhub/) applications.