docs: add summary_overview template#767

gcf-owl-bot[bot] wants to merge 1 commit intomaingoogleapis/python-bigquery-storage:mainfrom

owl-bot-update-lock-db05f70829de86fe8e34ba972b7fe56da57eaccf1691f875ed4867db80d5cec9googleapis/python-bigquery-storage:owl-bot-update-lock-db05f70829de86fe8e34ba972b7fe56da57eaccf1691f875ed4867db80d5cec9Copy head branch name to clipboard