Fixed long_description issue which prevented us from publishing whoos…

…h-reloaded to PyPi.

setup.py

@@ -38,7 +38,8 @@ def run_tests(self):
         author_email="[email protected]",
         maintainer="Sygil-Dev",
         description="Fast, pure-Python full text indexing, search, and spell checking library.",
-        long_description=open("README.md").read(),
+        long_description=open("README.md", "r").read(),
+        long_description_content_type="text/markdown",
         license="Two-clause BSD license",
         keywords="index search text spell",
         url="https://github.com/Sygil-Dev/whoosh-reloaded",