ADR: Design simplified system lifecycle for example system in tutorials

[nikitawootten-nist]

Committer Notes

Relates to #1893

Note: This ADR is numbered 0009 even though presently develop does not contain 0008, which is currently in a state of review

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• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
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Changes to Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your core changes, as applicable?
• Have you included examples of how to use your new feature(s)?
• Have you updated all OSCAL website and readme documentation affected by the changes you made? Changes to the OSCAL website can be made in the docs/content directory of your branch.

[iMichaela]

LGTM. Thank you.