Add link to conda-forge integration (#1687)

* Add link to conda-forge integration

resolves #1686

* README: keep PyPI tags together

Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com>

README.md

@@ -11,6 +11,7 @@
 <a href="https://github.com/psf/black/blob/master/LICENSE"><img alt="License: MIT" src="https://black.readthedocs.io/en/stable/_static/license.svg"></a>
 <a href="https://pypi.org/project/black/"><img alt="PyPI" src="https://img.shields.io/pypi/v/black"></a>
 <a href="https://pepy.tech/project/black"><img alt="Downloads" src="https://pepy.tech/badge/black"></a>
+<a href="https://anaconda.org/conda-forge/black/"><img alt="conda-forge" src="https://img.shields.io/conda/dn/conda-forge/black.svg?label=conda-forge"></a>
 <a href="https://github.com/psf/black"><img alt="Code style: black" src="https://img.shields.io/badge/code%20style-black-000000.svg"></a>
 </p>