Add contributors and README reference on PyPi (#12)

Author: iMicknl

README.md

@@ -50,5 +50,9 @@ for letter in letters:
 ## Changelog
 See the [CHANGELOG](./CHANGELOG.md) file.
 
+## Contributors
+- [@eavanvalkenburg](https://github.com/eavanvalkenburg)
+- [@peternijssen](https://github.com/peternijssen)
+
 ## License
 MIT

setup.py

@@ -3,7 +3,9 @@
 setup(
     name="postnl_api",
     version="1.2.0",
-    description="Python wrapper for the PostNL API, a way to track packages using their online portal",
+    description="Python wrapper for the PostNL API, a way to track packages and letters.",
+    long_description=open('README.md').read(),
+    long_description_content_type="text/markdown",
     url="https://github.com/imicknl/python-postnl-api",
     author="Mick Vleeshouwer",
     author_email="mick@imick.nl",