Updating copyright date

We are using this script for all our Tableau content.

Author: d45

docs/_includes/footer.html

@@ -3,6 +3,6 @@
     <div class="row">
         <hr class="footer-hr">
         <p>This site is open source. Suggestions and pull requests are welcome on our <a href="https://github.com/tableau/document-api-python">GitHub page</a>.</p>
-        <p>(c) Copyright 2016 Tableau</p>
+        <p>&copy; Copyright <script>document.write(new Date().getFullYear())</script> Tableau</p>
     </div>
 </footer>