Enhance the KubeVirt user-guide repository with comprehensive documentation for the newly introduced VideoConfig feature.
The documentation should provide clear guidance for users on how to configure video devices in VirtualMachines and understand the supported models per architecture.

Documentation Scope:

• Add a new section describing the VideoConfig feature and its purpose.

• List the supported video models (e.g., qxl, virtio, etc.) for each architecture (e.g., x86_64, aarch64).

• Include examples of VirtualMachine manifests demonstrating the use of spec.domain.devices.video.

• Document how to enable the VideoConfig feature gate, including from which KubeVirt version it is available.

• Clarify default behavior when the feature gate is disabled.

• Cross-reference related sections in the VEP and API documentation for deeper technical details.