Fix badge links

Author: RemyLau

README.md

@@ -1,7 +1,7 @@
-![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.5727847.svg)
-![Documentation Status](https://readthedocs.org/projects/pecanpy/badge/?version=latest)
-![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)
-![Tests](https://github.com/krishnanlab/PecanPy/actions/workflows/tests.yml/badge.svg)
+[![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.5838188.svg)](https://doi.org/10.5281/zenodo.5838188)
+[![Documentation Status](https://readthedocs.org/projects/pecanpy/badge/?version=latest)](https://pecanpy.readthedocs.io/en/latest/?badge=latest)
+[![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
+[![Tests](https://github.com/krishnanlab/PecanPy/actions/workflows/tests.yml/badge.svg)](https://github.com/krishnanlab/PecanPy/actions/workflows/tests.yml)
 
 # PecanPy: A parallelized, efficient, and accelerated _node2vec(+)_ in Python