Added Black formatting badge

Author: evaherrada

README.rst

@@ -13,6 +13,10 @@ Introduction
     :target: https://github.com/adafruit/Adafruit_CircuitPython_RA8875/actions/
     :alt: Build Status
 
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+    :target: https://github.com/psf/black
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 This is a full featured CircuitPython Library for the RA8875 that included all of the hardware
 accelerated drawing functions as the original Arduino library. A lot of the functionality has
 been streamlined with a focus on ease of use that is still flexible enough to make full use of