Fix BigQuery credentials link
Fix BigQuery credentials link

Closes #1706

Author: Phillip Cloud <cpcloud@gmail.com>

Closes #1726 from cpcloud/gh-1706 and squashes the following commits:

29a3f4e [Phillip Cloud] Fix BigQuery credentials link

ibis-project/ibis,cpcloud/ibis,ibis-project/ibis,cpcloud/ibis,cpcloud/ibis,ibis-project/ibis,cloudera/ibis,cpcloud/ibis,ibis-project/ibis,cloudera/ibis,cloudera/ibis