Provide documentation on ScheduleRecurrence attributes

It would be great if the documentation for **ScheduleRecurrence** contained details of attributes available, such as `start_time` and `frequency,` to name a few.

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#### Document Details

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* ID: f0c1f147-ad80-f801-ba15-8d1defa75956
* Version Independent ID: 09a74dd0-d7da-6611-4f0d-3a077851e7af
* Content: [azureml.pipeline.core.ScheduleRecurrence class - Azure Machine Learning Python](https://docs.microsoft.com/en-us/python/api/azureml-pipeline-core/azureml.pipeline.core.schedulerecurrence?view=azure-ml-py)
* Content Source: [AzureML-Docset/stable/docs-ref-autogen/azureml-pipeline-core/azureml.pipeline.core.ScheduleRecurrence.yml](https://github.com/MicrosoftDocs/MachineLearning-Python-pr/blob/live/AzureML-Docset/stable/docs-ref-autogen/azureml-pipeline-core/azureml.pipeline.core.ScheduleRecurrence.yml)
* Service: **machine-learning**
* Sub-service: **core**
* GitHub Login: @DebFro
* Microsoft Alias: **debfro**