Add PyPi long description (#93)

setup.py

@@ -1,13 +1,21 @@
 """Setup module for zigpy-xbee"""
 
+import os
+
 from setuptools import find_packages, setup
 
 import zigpy_xbee
 
+this_directory = os.path.join(os.path.abspath(os.path.dirname(__file__)))
+with open(os.path.join(this_directory, "README.md"), encoding="utf-8") as f:
+    long_description = f.read()
+
 setup(
     name="zigpy-xbee-homeassistant",
     version=zigpy_xbee.__version__,
     description="A library which communicates with XBee radios for zigpy",
+    long_description=long_description,
+    long_description_content_type="text/markdown",
     url="http://github.com/zigpy/zigpy-xbee",
     author="Russell Cloran",
     author_email="rcloran@gmail.com",