Add concrete Artifact name helper tipps in the devguard documentation for an artifact name

[timbastin]

While debugging an issue I saw an artifact name which did contain the version already. This is discouraged in devguard since we have logic in place which adds the assetVersionName as version to an artifact purl.

Thus an artifact name already containing a version will produce an invalid purl.

pkg:golang/whatever@main -> pkg:golang/whatever@main@main

[seb-kw]

Would suggest to also cross-check that in web via input validation.