Add Auth0 sponsor banner

Author: jpadilla

README.rst

@@ -16,9 +16,16 @@ PyJWT
 .. image:: https://readthedocs.org/projects/pyjwt/badge/?version=latest
    :target: https://pyjwt.readthedocs.io
 
-A Python implementation of `RFC
-7519 <https://tools.ietf.org/html/rfc7519>`_. Original implementation
-was written by `@progrium <https://github.com/progrium>`_.
+A Python implementation of `RFC 7519 <https://tools.ietf.org/html/rfc7519>`_. Original implementation was written by `@progrium <https://github.com/progrium>`_.
+
+Sponsor
+-------
+
++--------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
+| |auth0-logo| | If you want to quickly add secure token-based authentication to Python projects, feel free to check Auth0's Python SDK and free plan at `auth0.com/overview <https://auth0.com/overview?utm_source=GHsponsor&utm_medium=GHsponsor&utm_campaign=pyjwt&utm_content=auth>`_. |
++--------------+-----------------------------------------------------------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
+
+.. |auth0-logo| image:: https://user-images.githubusercontent.com/83319/31722733-de95bbde-b3ea-11e7-96bf-4f4e8f915588.png
 
 Installing
 ----------