docs(vdsnapshot): update consistency info

[hardcoretime]

Why do we need it, and what problem does it solve?

This change is necessary to improve the explanation about working with virtual disk snapshots.

Checklist

• The code is covered by unit tests.
• e2e tests passed.
• Documentation updated according to the changes.
• Changes were tested in the Kubernetes cluster manually.

Changelog entries

section: vdsnapshot
type: docs
summary: "Update virtual disk snapshot consistency information."
impact_level: low