update rfc with most recent updates

[alegrey91]

1. Force scan annotation: Add force-node-scan: "true" annotation mechanism for triggering immediate scans, with auto-removal after completion.
2. scanInterval is mandatory: Mark as (required) and updated the surrounding text to clarify NodeScanConfiguration is primarily for periodic scans.
3. NodeScanJob requires NodeScanConfiguration: Clarify that without a NodeScanConfiguration, users cannot apply a NodeScanJob, since it holds the configuration used by all jobs.
4. Inverted owner references: NodeScanConfiguration now owns NodeScanJob and NodeSBOM (Kubernetes GC handles deletion), while Node deletion triggers client-side cleanup by the controller.