Use and document Trivy JSON report schema version 2 in the Trivy documentation

[fniessink]

Description

When generating a Trivy report with JSON format (for example trivy image --debug --offline-scan --input target/tar_images/example_image.tar -f json -o target/testresults/trivy/trivy-results.json), it uses schema version 2 as discussed here. However, the documentation shows an example conform schema version 1 and there's no mention of a schema.

Link

https://aquasecurity.github.io/trivy/v0.55/docs/configuration/reporting/#json

Suggestions

1. Update the example JSON report to conform to schema version 2.
2. Document schema version 2 as part of the documentation.

[knqyf263]

Both suggestions make sense to me. Created #7553. Thanks.