Add long_description_content_type to setup function call

Author: zliang-akamai

setup.py

@@ -72,6 +72,7 @@ def bake_version(v):
 
     description='The official python SDK for Linode API v4',
     long_description=long_description,
+    long_description_content_type="text/x-rst",
 
     # The project's main homepage.
     url='https://github.com/linode/linode_api4-python',