docs: Add a long_description.

The default empty long_description is failing  when we try to push it to
PyPI so make the README the long_description and be clear that it's
markdown and not RST.

setup.py

@@ -2,6 +2,7 @@
 """ Setup to allow pip installs of edx-search module """
 import os
 import re
+from pathlib import Path
 
 from setuptools import setup
 
@@ -47,11 +48,16 @@ def get_version(*file_paths):
 
 VERSION = get_version('edxsearch', '__init__.py')
 
+# read the contents of your README file
+this_directory = Path(__file__).parent
+long_description = (this_directory / "README.md").read_text()
 
 setup(
     name='edx-search',
     version=VERSION,
     description='Search and index routines for index access',
+    long_description=long_description,
+    long_description_content_type='text/markdown',
     author='edX',
     author_email='oscm@edx.org',
     url='https://github.com/openedx/edx-search',