Add k0s distribution support to etcdctl-wrapper

[Copilot]

The wrapper script only detected k3s and vanilla Kubernetes cert directories, leaving k0s clusters without auto-TLS configuration.

Changes

• etcdctl-wrapper.sh: Added k0s branch in the cert-dir detection chain, between k3s and vanilla k8s checks:
  • Cert dir: /host/var/lib/k0s/pki/etcd/
  • Files: ca.crt, server.crt, server.key
• Readme.md: Updated the "Where to run it" and "How auto-TLS works" tables to include k0s (controller nodes)

K0S_CERT_DIR="/host/var/lib/k0s/pki/etcd"
...
elif [ -d "$K0S_CERT_DIR" ]; then
    CACERT="$K0S_CERT_DIR/ca.crt"
    CERT="$K0S_CERT_DIR/server.crt"
    KEY="$K0S_CERT_DIR/server.key"