1.29 - website: add volumeattributesclass doc

[sunnylovestiramisu]

https://kubernetes.io/docs/concepts/storage/persistent-volumes#volumeattributesclass
https://kubernetes.io/docs/concepts/storage/volume-attributes-classes/

[sunnylovestiramisu]

kubernetes/website#43463 is merged

[sunnylovestiramisu]

This is done

/close

[k8s-ci-robot]

@sunnylovestiramisu: Closing this issue.

In response to this:

This is done

/close

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