Fixed non-valid rst in README

Author: absurdfarce

README.rst

@@ -58,7 +58,7 @@ Contributing
 See `CONTRIBUTING.md <https://github.com/datastax/python-driver/blob/master/CONTRIBUTING.rst>`_.
 
 Error Handling
-------------
+--------------
 While originally written for the Java driver, users may reference the `Cassandra error handling done right blog <https://www.datastax.com/blog/cassandra-error-handling-done-right>`_ for resolving error handling scenarios with Apache Cassandra.
 
 Reporting Problems