documentation for pagebuilder row widget is incomplete

There is no information in the document on how to unset/remove a background image. it seems that once you set a background image it is impossible to remove it.

https://experienceleague.adobe.com/en/docs/commerce-admin/page-builder/layout/row

https://github.com/AdobeDocs/commerce-admin.en/blob/main/help/page-builder/row.md

Start with help/page-builder/row.md and compare it with the linked Adobe Commerce Row documentation. Verify in the Page Builder row widget how a background image is unset or removed, then document those steps in the row guide. Done means the page explains how to remove an existing background image.

Written by the indexing model from the issue text.