Update README.md

Add pypi and bioconda download badges

Author: jeromekelleher

README.md

@@ -1,5 +1,7 @@
 [![CI](https://github.com/sgkit-dev/bio2zarr/actions/workflows/ci.yml/badge.svg?branch=main)](https://github.com/sgkit-dev/bio2zarr/actions/workflows/ci.yml)
 [![Coverage Status](https://coveralls.io/repos/github/sgkit-dev/bio2zarr/badge.svg)](https://coveralls.io/github/sgkit-dev/bio2zarr)
+[![PyPI Downloads](https://static.pepy.tech/badge/bio2zarr)](https://pepy.tech/projects/bio2zarr)
+[![Anaconda-Server Badge](https://anaconda.org/bioconda/bio2zarr/badges/downloads.svg)](https://anaconda.org/bioconda/bio2zarr)
 
 
 # bio2zarr