website: footer.html: really use version 1.7.1 of clipboard.js

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

docs/website/footer.html

@@ -1,6 +1,6 @@
 	<script src="https://code.jquery.com/jquery-3.1.1.min.js"></script>
 	<script src="https://oss.maxcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
-	<script src="https://cdn.rawgit.com/zenorocha/clipboard.js/v2.0.0/dist/clipboard.min.js"></script>
+	<script src="https://cdn.rawgit.com/zenorocha/clipboard.js/v1.7.1/dist/clipboard.min.js"></script>
 	<script type="text/javascript" src="js/buildroot.js"></script>
 </body>
 </html>