documentation: align kubernetes example with the community

[paulfantom]

Throughout the last few years, there was a lot of development in the area of prometheus integration with kubernetes. During that time we have established some guidelines in how to name a few common, identifying labels to allow easy consumption of monitoring mixins, solidify integration between various tools, and improve UX. Some of those guidelines even got into prometheus documentation in the form of code comments -https://github.com/prometheus/prometheus/blob/main/documentation/prometheus-mixin/config.libsonnet#L24.

This PR is an attempt to merge two conflicting guidelines, one that is advertised by prometheus as an example configuration and the other that is widely used by prometheus-operator, monitoring mixins, and other tools (like kube-state-metrics).

Since this is changing only an example configuration, I do not see this as a breaking change. However, I am open to being convinced otherwise :)

This is related to prometheus-operator/prometheus-operator#4415

/cc @brancz @simonpasquier

[brancz]

Completely agree. It also aligns with the Kubernetes structured logging conventions and the general instrumentation conventions. As a matter of fact it has probably been damaging that we've had these two documented for so long. Thank you so much for opening this!