Add DOI badge to README

Added a DOI badge to the README for citation purposes.

Author: thewtex

README.md

@@ -1,5 +1,7 @@
 # OME-Zarr Open SciVis Datasets
 
+[![DOI](https://zenodo.org/badge/856568248.svg)](https://doi.org/10.5281/zenodo.17495293)
+
 ![engine](./thumbnails/small/engine.webp)
 
 > The [OME-Zarr Open SciVis Datasets](https://registry.opendata.aws/ome-zarr-open-scivis/) project provides the Open SciVis Dataset in a chunked, multi-scale format, encodes metadata in JSON according to the OME-Zarr specification, and hosts the datasets on AWS S3 through the AWS Open Data Program, aiming to serve as a web-based resource for the scientific visualization community to enhance reproducibility and facilitate testing and development of OME-Zarr tools.