Explicitly mention OME-Zarr support

[dstansby]

There's a section in the docs about support for Zarr, but I understand there's also support for OME-Zarr? If so it would be nice to explicitly add this to the integrations list at https://itkwidgets.readthedocs.io/en/latest/integrations.html#zarr

[thewtex]

Yes, itkwidgets is built around the OME-Zarr data model 👍