Added a badge for black

README.md

@@ -1,6 +1,6 @@
 # momw
 
-[![Build Status](https://buildbot.modding-openmw.com/badges/1.svg)](https://buildbot.modding-openmw.com/#/builders/1)
+[![Build Status](https://buildbot.modding-openmw.com/badges/1.svg)](https://buildbot.modding-openmw.com/#/builders/1) [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/python/black)
 
 Source code for the modding-openmw.com website