Add documentation for (amongst others) kube_deployment_status_replicas_unavailable #2799
Description
What would you like to be added:
There is no 'official' documentation on kube_deployment_status_replicas_unavailable on a kubernetes website - only via third party resources like https://docs.cloudera.com/management-console/1.5.4/monitoring-metrics/topics/cdppvc_ds_kube_deployment_status_replicas_unavailable_trics.html. I would like this to be added (or made more find-able).
Why is this needed:
Lack of documentation leads to some uncertainty about the stability/actual 'inner workings' of this important metric.
Describe the solution you'd like:
Documentation on e.g. https://kubernetes.io/docs/reference/instrumentation/metrics/ or a more suitable place.
Additional context:
I'm happy to document it, if you provide a pointer as to where.
