Add example s3 uri to user guide

[tkilias]

Background

• the s3 formats for the export of the data and for output of the model use different formats.
• the export of data needs credentials which are given as a connection object
• the output of the model is done by the sagemaker roles which needs access to the output bucket
• here and example for the connection
  • https://github.com/exasol/sagemaker-extension/blob/3057e6096726a28ffd5898c9023300888965f235/tests/ci_tests/fixtures/prepare_environment_fixture.py#L62
• here an example for s3_output parameter
  • https://github.com/exasol/sagemaker-extension/blob/3057e6096726a28ffd5898c9023300888965f235/tests/ci_tests/fixtures/prepare_environment_fixture.py#L195

Acceptance Criteria

• Example uri for the create connection
• Example uri for the s4 output parameter