Improve documentation for test-suite

[MartinWheelerMT]

What

• Improve documentation for test-suite.

Why

To better explain the prerequisites and the steps needed to ensure the test has run correctly.

Type of change

Please delete options that are not relevant.

• Internal change (non-breaking change with no effect on the functionality affecting end users)

Checklist:

• I have performed a self-review of my code
• I have made corresponding changes to the documentation where required
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have updated the Changelog with details of my change in the UNRELEASED section if this change affects end users.

[github-actions]

Images built and published to ECR using a Build Id of PR-266-1bcff1f