[opentelemetry] add labels according to naming convention

[timojohlo]

Context

In a future version of OpenTelemtry we want to provide extended labels that describe each log-line based on source, host, environment etc.

Acceptance Criteria

• Discuss and align on best-pratice labeling
• Implement labeling/attributes for each source (k8s events, container logs, journal logs etc.) where possible
• Document label-approach

References

https://opentelemetry.io/docs/specs/semconv/resource/

Example

Attributes are grouped logically by the type of the concept that they described. Attributes in the same group have a common prefix that ends with a dot. For example all attributes that describe Kubernetes properties start with “k8s.”

[Kuckkuck]

Added Kubernetes labels according to Opentelemetry Kubernetes specs.

Pull request #369

the following labels are not available:
k8s.container.status.last_terminated_reason
k8s.cronjob.uid

[Kuckkuck]

First version of labels are part of the OpeneTelemetry logs collector config.