update setup.py

Author: irahorecka

setup.py

@@ -13,7 +13,8 @@
     license="MIT",
     description="Simple Alameda-Contra Costa Transit District (AC Transit) API wrapper",
     version="v0.1.6",
-    long_description=README,
+    long_description="README.md",
+    long_description_content_type="text/markdown",
     url="https://github.com/irahorecka/python-actransit",
     packages=["actransit"],
     python_requires=">=3.8",