Tutorial: Including evidence in an assessment result

[david-waltermire]

User Story:

As an OSCAL {stakeholder}, I need guidance on and examples of how to include assessment evidence in an OSCAL assessment result based on the assessment of a given control.

Goals:

• Illustrate how to associate evidence as part of an observation in an OSCAL assessment result.

Dependencies:

{Describe any previous issues or related work that must be completed to start or complete this issue.}

Acceptance Criteria

• [ ] All OSCAL website and readme documentation affected by the changes in this issue have been updated. Changes to the OSCAL website can be made in the docs/content directory of your branch.
• [ ] A Pull Request (PR) is submitted that fully addresses the goals of this User Story. This issue is referenced in the PR.
• [ ] The CI-CD build process runs without any reported errors on the PR. This can be confirmed by reviewing that all checks have passed in the PR.

[aj-stein-nist]

Marking this as blocked until #1910 is completed, and then it will be ready for "Needs Refinement" and determination if we edit this issue or replace it with a different one.