Sample Tasks Docs Improvements

[peterhessey]

Is there an existing issue for this?

• [X] I have searched the existing issues

Issue summary

The steps for the lung example model detailed in sample_tasks.md are currently broken - running the dataset conversion gives the following error:

System.AggregateException: One or more errors occurred. ---> System.Exception: Folder contained multiple series.

What documentation should be provided?

New steps that outline how to run the dataset conversion without issue.

AB#6571