text: Title: Update README with new Demo API
  Body: ## Description
  
  We need to update the examples in the README.md file that uses demo.scanapi.dev/api/. We've [changed the API](https://github.com/scanapi/demo-api/issues/16) and the doc should reflect that.
  
  Old API: https://demo.scanapi.dev/api/
  New API: https://demo.scanapi.dev/