Inconsitent description for apiVersion

[JPinkney]

apiVersion under kubernetes_ObjectFieldSelector lists the description as "version of the schema that fieldPath is written in terms of; defaults to v1" and does not have default values.

apiVersion under kubernetes_ObjectReference lists the description as "API version of the referent" and doesn't have default values

All other references of apiVersion have description as an empty string.

This creates a problem when implementing a langauge server for kubernetes: https://github.com/gorkem/vscode-k8s