Add README to PyPI page

setup.py

@@ -1,3 +1,5 @@
+from pathlib import Path
+
 from setuptools import setup
 
 test_deps = [
@@ -26,9 +28,14 @@ extras = {
     "blurhash": blurhash_deps,
 }
 
+this_directory = Path(__file__).parent
+long_description = (this_directory / "README.rst").read_text()
+
 setup(name='Mastodon.py',
       version='1.8.0',
       description='Python wrapper for the Mastodon API',
+      long_description=long_description,
+      long_description_content_type='text/x-rst',
       packages=['mastodon'],
       install_requires=[
           'requests>=2.4.2',