Clarify BackendRef Port API Doc #3840
Description
The backendRef port definition is vague for non-Service references, which is confusing:
// Port specifies the destination port number to use for this resource.
// Port is required when the referent is a Kubernetes Service. In this
// case, the port number is the service port number, not the target port.
// For other resources, destination port might be derived from the referent
// resource or this field.
//
// +optional
Port *PortNumber `json:"port,omitempty"`