Update README.md

Author: dynata-bradley

README.md

@@ -31,6 +31,7 @@ A Python client library for the [Dynata Cmix API](https://wiki2.criticalmix.net/
     get_surveys(status, *args, **kwargs)
     get_survey_definition(survey_id)
     get_survey_xml(survey_id)
+    get_survey_simulations(survey_id)
     get_survey_test_url(survey_id)
     get_survey_respondents(survey_id, respondent_type, live)
     get_survey_status(survey_id)