Update README_TESTS.md

Author: p-zielinski

__tests__/README_TESTS.md

@@ -56,6 +56,8 @@ Test example:
 `.env` file shall be in the root of the project and shall contain `X_APP_ID`, `X_APP_TOKEN` and `VOUCHERIFY_HOST` variables. Check `.env.example` for reference.
 
 ## Run tests:
+
+From the root of the project run:
 ```bash
 php vendor/bin/codecept run Unit
 ```