POM: clarify project description
POM: clarify project description

Saying "all Open Microscopy Environment formats" could be misconstrued
as including all formats supported by Bio-Formats, even PFFs -- whereas
what this project actually provides is support for the OME-XML data
model, and the OME-XML and OME-TIFF file formats.

scifio/scifio-ome-xml