[exporter/loki] The docs for loki.resource.labels is incorrect

[Jontem]

Describe the issue you're reporting

In the example and readme it's shown that loki.resource.labels should be placed under resource processor.

  resource:
    attributes:
    - action: insert
      key: loki.resource.labels
      value: host_name, pod_name

But i couldn't get it to work. Looking at the actual implementation it seems that it looks for resourceHints in log attributes
https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/pkg/translator/loki/convert.go#L48

// get the hint from the log attributes, not from the resource
// the value can be a single resource name to use as label
// or a slice of string values
if resourcesToLabel, found := logAttrs.Get(hintResources); found {
  labels := convertAttributesToLabels(resAttrs, resourcesToLabel)
  out = out.Merge(labels)
}

[github-actions]

Pinging code owners: @gramidt @gouthamve @jpkrohling @kovrus @mar4uk. See Adding Labels via Comments if you do not have permissions to add labels yourself.

[kovrus]

@Jontem @zirain you are right, it seems like a bug. Do you want to open a pull request with a fix?

[zirain]

cc @kovrus #16088