docs: update access form to short URL (#11)

* docs: update access form to short URL

Updating the link to point to shortened form, so if there are any
changes in the future, we won't need to update the README again.

README.rst

@@ -12,7 +12,7 @@ and answer service for BigQuery data.
 .. warning::
    Data QnA is currently in private Alpha. Access is only available to
    allowlisted users. Apply for access
-   `here <https://docs.google.com/forms/d/e/1FAIpQLSc4Vszsmm6LrPT1MoNbC074SYCMBXB8tps6OEmdmg9zBgo3TA/viewform>`_.
+   `here <http://g.co/cloud/data-qna>`_.
 
 .. |alpha| image:: https://img.shields.io/badge/support-alpha-orange.svg
    :target: https://github.com/googleapis/google-cloud-python/blob/master/README.rst#alpha-support