Improve documentation

Author: florijanstamenkovic

README.md

@@ -64,3 +64,10 @@ task.wait_till_done()
 
 # Your data is now uploaded to Labelbox and ready for labeling!
 ```
+
+### Documentation and API specification
+
+Documentation for the Labelbox Python Client package can be found at
+https://labelbox.helpdocs.io/docs/python-client-api. The API documentation
+is available at
+https://labelbox.helpdocs.io/docs/python-client-api/api-specification.