add documentation

README.md

@@ -1,4 +1,5 @@
 # REST API Python
+### <a href="https://documenter.getpostman.com/view/18312872/UzBjrSwk">Documentation</a>
 ## Instruction
 1. Change config.py
 2. Open **cmd** and go to ```cd C:/your_path/pythoRestApi/rest_api_venv/Scripts```