[Docker Integration] Update information for metrics

[gizas]

Docker Integration supports different metrics like container, cpu, diskio, healthcheck, info, memory and network. Also since 8.16.2, support of metrics from Podman’s Docker-compatible API has been introduced. It has been observed that different metrics are being populated if we compare cgroupsv2 vs cgroupsv1 underlying OS architecture

In more details we notice that always in cgroupsv2 the below are null:

    "io_serviced_recursive": null,
    "io_queue_recursive": null,
    "io_service_time_recursive": null,
    "io_wait_time_recursive": null,
    "io_merged_recursive": null,
    "io_time_recursive": null,
    "sectors_recursive": null

Comparing fs v1 vs fs v2 those group of metrics are not simply provided.

Docker integration relies on the response of the stats api and if those are nill we just return those metrics are zero.
It seems in general that v2 has changed to this output

Goals:

• All this information for diskio category should be documented
• Provide alternative metrics for each category if is possible for users in order to evaluate io utilisation.