Create documentation for archive container scanning

What does this MR do and why?

With the implementation of Support tar file scanning (gitlab-org/security-products/analyzers/container-scanning!3151 - merged) we should document this capability and its usage and flow. This MR creates this documentation.

This is part of the implementation plan for Archive File Scanning for Container Scanning (#501077 - closed)

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

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