[1.16] Clarify Service Account token requirements for secretKeyRef with auto-loaded Kubernetes secret store

[MyMirelHub]

Describe the issue
The Service Account tokens section states that component secrets don't require a token, but omits that Dapr auto-loads a built-in Kubernetes secret store in the sidecar that requires a token to initialize. This causes pods to crash with stat /home/nonroot/.kube/config: no such file or directory when using automountServiceAccountToken: false.

URL of the docs
https://docs.dapr.io/operations/hosting/kubernetes/kubernetes-production/#service-account-tokens

Expected content
Documentation should clarify that:

1. The Operator resolves secretKeyRef without a pod token (works as stated)
2. The sidecar auto-loads a Kubernetes secret store that needs a token
3. Use annotation dapr.io/disable-builtin-k8s-secret-store: "true" to run with automountServiceAccountToken: false