Add nvme devices to disk metrics

[osterik]

Currently, NVME* devices don't show in "CPU / Memory / Net / Disk" row
Not sure if it's the best way to add it, but it works for me :)

[candlerb]

Another way is to define a hidden dashboard variable (which makes it easier for other people to tweak if necessary)

              "expr": "irate(node_disk_reads_completed_total{instance=\"$node\",job=\"$job\",device=~\"$diskdevices\"}[5m])",

...

      {
        "allValue": null,
        "current": {
          "selected": false,
          "text": "[a-z]+|nvme[0-9]+n[0-9]+",
          "value": "[a-z]+|nvme[0-9]+n[0-9]+"
        },
        "hide": 2,
        "includeAll": false,
        "label": null,
        "multi": false,
        "name": "diskdevices",
        "options": [
          {
            "selected": true,
            "text": "[a-z]+|nvme[0-9]+n[0-9]+",
            "value": "[a-z]+|nvme[0-9]+n[0-9]+"
          }
        ],
        "query": "[a-z]+|nvme[0-9]+n[0-9]+",
        "skipUrlSync": false,
        "type": "custom"
      }

I've done this in 12486