Add CITATION.cff file (#3723)

Author: schackartk

CHANGES.md

@@ -84,6 +84,9 @@
 
 ### Documentation
 
+- Add a CITATION.cff file to the root of the repository, containing metadata on how to
+  cite this software (#3723)
+
 <!-- Major changes to documentation and policies. Small docs changes
      don't need a changelog entry. -->
 

CITATION.cff

@@ -0,0 +1,22 @@
+cff-version: 1.2.0
+title: "Black: The uncompromising Python code formatter"
+message: >-
+  If you use this software, please cite it using the metadata from this file.
+type: software
+authors:
+  - family-names: Langa
+    given-names: Łukasz
+  - name: "contributors to Black"
+repository-code: "https://github.com/psf/black"
+url: "https://black.readthedocs.io/en/stable/"
+abstract: >-
+  Black is the uncompromising Python code formatter. By using it, you agree to cede
+  control over minutiae ofhand-formatting. In return, Black gives you speed,
+  determinism, and freedom from pycodestyle nagging about formatting. You will save time
+  and mental energy for more important matters.
+
+  Blackened code looks the same regardless of the project you're reading. Formatting
+  becomes transparent after a while and you can focus on the content instead.
+
+  Black makes code review faster by producing the smallest diffs possible.
+license: MIT