The Google Docs Add-on is published in the Chrome Webstore, and is accessible from within Google Docs by going to “Add-ons” -> “Get Add-ons” and searching for “BibleGet” or “BibleGet I/O”.
Or, you can use this direct link to the listing in the Chrome Webstore, clicking on the Webstore Badge:
To insert the desired bible quote into your document, open the sidebar by clicking on “Start” from “Add-ons -> BibleGet I/O”. Write the query for the desired verses using standard notation and click on “Search”. A preview of the verses will be shown in the preview box. Set your desired formatting from the “Format” tab and then insert the verses into your document by clicking on “Insert into document” (back in the “Search Quote” tab).