Add Distances field to machine.Node

[PiotrProkop]

Add information about NUMA distances to Node struct.

[k8s-ci-robot]

Hi @PiotrProkop. Thanks for your PR.

I'm waiting for a google member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[Creatone]

/ok-to-test

[Creatone]

Could you extend the metrics?
https://github.com/google/cadvisor/blob/master/metrics/prometheus_machine.go#L156

And describe the new one in the docs?
https://github.com/google/cadvisor/blob/master/docs/storage/prometheus.md#prometheus-hardware-metrics

[PiotrProkop]

@Creatone thanks for review, metrics updated

[Creatone]

Small nit and it can be merged 👍

[Creatone]

LGTM