`:plone:` failed build http://hudson.openmicroscopy.org.uk/view/Docs/job/BIOFORMATS-docs-merge-4.4/217/console with:

```
Warning, treated as error:
/home/hudson/.hudson/jobs/BIOFORMATS-docs-merge-4.4/workspace/docs/sphinx/formats/3i-slidebook-metadata.txt:7: ERROR: Unknown interpreted text role "plone".
```