Added release notes for python-pillow#7599 and python-pillow#7593

Author: radarhere

docs/releasenotes/10.2.0.rst

@@ -54,3 +54,11 @@ Support has been added to read the BC4U format of DDS images.
 
 Support has also been added to read DX10 BC1 and BC4, whether UNORM or
 TYPELESS.
+
+Optimized ImageStat.Stat count and extrema
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Calculating the :py:attr:`~PIL.ImageStat.Stat.count` and
+:py:attr:`~PIL.ImageStat.Stat.extrema` statistics is now faster. After the
+histogram is created in ``st = ImageStat.Stat(im)``, ``st.count`` is 3x as fast
+on average and ``st.extrema`` is 12x as fast on average.