Collect Kubernetes advisories

There is a mostly unstructured JSON feed and web page at:
- web page at https://kubernetes.io/docs/reference/issues-security/official-cve-feed/
- JSON "index" https://kubernetes.io/docs/reference/issues-security/official-cve-feed/index.json
- assembled here https://github.com/kubernetes/website/tree/main/content/en/docs/reference/issues-security
- ... which mostly points to issues like in https://github.com/kubernetes/kubernetes/issues/74534 , a CVE and links ...
- to a Google groups: https://groups.google.com/g/kubernetes-announce/c/ufYd_aq4Y20/m/V3LKIffxCAAJ

This is managed by https://github.com/kubernetes/committee-security-response/blob/main/README.md#product-security-committee-psc but is mostly unusable as-is and demands complex parsing or manual handling.

Of interest, advisories like this https://groups.google.com/g/kubernetes-announce/c/ufYd_aq4Y20/m/V3LKIffxCAAJ do not point to a package proper, but to a family of container images built with a specific tool version.