Update batch image export tutorial link

client tutorials in the main docs have been replaced by the 'help' guides for some time but this script was still pointing at a link which doesn't exist anymore.
merge develop -D org: PR 85 (Update batch image export tutorial link)
merge develop -D org

Repository: ome/scripts
Already up-to-date.

Merged PRs:
  # PR 85 hflynn 'Update batch image export tutorial link'
Generated by OMERO-5.1-merge-push#309 (http://ci.openmicroscopy.org/job/OMERO-5.1-merge-push/309/)