Update README.md

Author: gjhuizing

README.md

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 [![Documentation Status](https://readthedocs.org/projects/mowgli/badge/?version=latest)](https://mowgli.readthedocs.io/en/latest/?badge=latest)
 [![PyPI version](https://img.shields.io/pypi/v/mowgli?color=blue)](https://img.shields.io/pypi/v/mowgli?color=blue)
 [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
+[![DOI](https://zenodo.org/badge/391909874.svg)](https://zenodo.org/badge/latestdoi/391909874)
 
 Mowgli is a novel method for the integration of paired multi-omics data with any type and number of omics, combining integrative Nonnegative Matrix Factorization and Optimal Transport. [Read the preprint!](https://www.biorxiv.org/content/10.1101/2023.02.02.526825v2)