Docs: Container scanning offline docs should emphasize image updates

• Start this issue's title with Docs: or Docs feedback:.

Problem to solve

Using container scanning in an offline environment requires that the Grype and Trivy images be regularly updated in the offline container registry. If a container image is more than 5 days old, vunlerability scanning of containers may fail with something like the following message:

the vulnerability database was built 6 days ago (max allowed age is 5 days)

Further details

Proposal

Make it clear in the following docs section that container images stored in an offline container registry must be regularly updated.

• https://docs.gitlab.com/user/application_security/container_scanning/#running-container-scanning-in-an-offline-environment

Who can address the issue

Anyone

Other links/references