Remove 2,505-line changelog from description

It made the PyPI listing page very long and requires a lot of scrolling to get down to the files, annoying for downstream packagers.

Instead it's linked from the README. 

[CI skip]

setup.py

@@ -721,9 +721,7 @@ setup(
     name=NAME,
     version=PILLOW_VERSION,
     description='Python Imaging Library (Fork)',
-    long_description=(
-        _read('README.rst') + b'\n' +
-        _read('CHANGES.rst')).decode('utf-8'),
+    long_description=_read('README.rst').decode('utf-8'),
     author='Alex Clark (fork author)',
     author_email='aclark@aclark.net',
     url='http://python-pillow.github.io/',