black: add badge to `README.md`

1 files changed, 1 insertions, 0 deletions

diff --git a/README.md b/README.md
index e8043672e5..df05837be8 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,7 @@
 [![codecov](https://codecov.io/gh/spack/spack/branch/develop/graph/badge.svg)](https://codecov.io/gh/spack/spack)
 [![Containers](https://github.com/spack/spack/actions/workflows/build-containers.yml/badge.svg)](https://github.com/spack/spack/actions/workflows/build-containers.yml)
 [![Read the Docs](https://readthedocs.org/projects/spack/badge/?version=latest)](https://spack.readthedocs.io)
+[![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
 [![Slack](https://slack.spack.io/badge.svg)](https://slack.spack.io)
 
 Spack is a multi-platform package manager that builds and installs