Which are the states including the common SFN states for which <state>.output () can be applied ?

This is a separate issue created from the discussion by @nsankar addressed to @wong-a from the issue id #31
The key point is which are the common SFN and AWS specific service states where we can use the form `.output()` in this SDK. Please include it in the documentation.

More details and an example state using output() is as under.,

(1) Which are the states including the common SFN states for which state output () is applicable **or** can be used? This is not in the document unless we see an example, for instance, as an example output () is applicable to the processing step which can be then used in a choice state as cited below:

```
processing_step = ProcessingStep(
"SageMaker processing step",
processor=script_processor,
job_name=execution_input["PreprocessingJobName"], ## placeholder per schema above. Later in workflow execute() below pass the uuid of jobname
inputs=inputs,
outputs=outputs,
# container_arguments=["--train-test-split-ratio", "0.2"],
container_entrypoint=["python3", "/opt/ml/processing/input/code/myprogram.py"],
)

choice_state1.add_choice(ChoiceRule.StringEquals(processing_step**.output()**["ProcessingJobStatus"], "Completed"), lambda_state1)

```

この issue では ProcessingStep、ChoiceRule.StringEquals、状態の出力 output() が挙げられていますが、ドキュメントファイルやテストは特定されていません。まず、ワークフロー状態に関する SDK ドキュメントと ProcessingStep の例を見つけ、次に、どの共通状態および AWS 固有の状態が output() をサポートしているかを確認してください。ドキュメントに該当する状態が一覧表示され、動作する例が含まれていれば完了です。

索引モデルが issue の本文から書いたものです。