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)

```

La issue cita ProcessingStep, ChoiceRule.StringEquals e l'output dello stato output(), ma non identifica alcun file di documentazione o test. Inizia individuando la documentazione dell'SDK sugli stati del workflow e l'esempio di ProcessingStep, quindi determina quali stati comuni e specifici di AWS supportano output(). Il lavoro è completo quando la documentazione elenca gli stati applicabili e include un esempio funzionante.

Scritto dal modello di indicizzazione a partire dal testo della issue.