Where to find complete documentation for CRDs?

I'm looking for the complete documentation for the ECK operator CRDs. For example, I'm looking into tweaking the config for Kibana pods so they may run on my cluster. I see that the CRD defines spec.podTemplate, but explain just says:

$ kubectl explain kibana.spec.podTemplate
KIND:     Kibana
VERSION:  kibana.k8s.elastic.co/v1

     PodTemplate provides customisation options (labels, annotations, affinity
     rules, resource requests, and so on) for the Kibana pods

etc. There is a PodTemplate object that can be found with kubectl explain PodTemplate, however it's not clear what values from that object must be specified when configuring ES, Kibana, etc, and what default settings are set by the operator. I'm concerned about overriding something critical, especially values in the annotations object and the containers array.