Consider signposting anchorectl for enterprise customers

We had some feedback from Anchore Enterprise customer support that customers are discovering [scan-action](https://github.com/anchore/scan-action) and [sbom-action](https://github.com/anchore/sbom-action), and expecting them to solve their Anchore Enterprise sbom/scan requirements.

The Anchore Enterprise supported tool is `anchorectl`.

We should consider a short, informational banner at the top of the marketplace entry, so enterprise users don't waste their time, and the CS team's time.

Start by locating the scan-action marketplace entry and its associated documentation. Add a short informational banner directing Anchore Enterprise customers to anchorectl, and verify that the marketplace text clearly distinguishes the supported enterprise tool from scan-action and sbom-action.

Written by the indexing model from the issue text.