CONTRIBUTING.rst: Remove section about CLA

It is talking about Datastax CLA, which is not required to contribute to
our fork. Afaik we don't have any CLA required for external contributors
to our drivers.

Author: Lorak-mmk

CONTRIBUTING.rst

@@ -20,10 +20,6 @@ Pull Requests
 If you're able to fix a bug yourself, you can `fork the repository <https://help.github.com/articles/fork-a-repo/>`_ and submit a `Pull Request <https://help.github.com/articles/using-pull-requests/>`_ with the fix.
 Please include tests demonstrating the issue and fix. For examples of how to run the tests, consult the `dev README <https://github.com/scylladb/python-driver/blob/master/README-dev.rst#running-the-tests>`_.
 
-Contribution License Agreement
-------------------------------
-To protect the community, all contributors are required to `sign the DataStax Contribution License Agreement <http://cla.datastax.com/>`_. The process is completely electronic and should only take a few minutes.
-
 Design and Implementation Guidelines
 ------------------------------------
 - We have integrations (notably Cassandra cqlsh) that require pure Python and minimal external dependencies. We try to avoid new external dependencies. Where compiled extensions are concerned, there should always be a pure Python fallback implementation.