Added new documentation url to readme

README.rst

@@ -25,6 +25,7 @@ attempt to familiarize yourself with the Pushshift API documentation to better u
 what search arguments are likely to work.
 
 * `API Documentation on github <https://github.com/pushshift/api>`_
+* Endpoints and parameter descriptions: https://pushshift.io/api-parameters/
 * `/r/pushshift <https://www.reddit.com/r/pushshift/>`_