docs: extend PVC test to include pod write + persistence check

Prior test only checked PVC reaches Bound. Add a pod that writes a
file, then a second pod re-mounting the same PVC to confirm data
survives pod delete/recreate (proves NFS-backed, not emptyDir).

README.md

@@ -195,9 +195,65 @@ EOF
 kubectl get pvc nfs-test
 ```
 
-Status should be `Bound`. Clean up:
+Status should be `Bound`.
+
+Test a pod actually writing to it:
 
 ```bash
+kubectl apply -f - <<'EOF'
+apiVersion: v1
+kind: Pod
+metadata:
+  name: nfs-test-pod
+  namespace: default
+spec:
+  containers:
+    - name: writer
+      image: busybox:1.36
+      command: ["sh", "-c", "echo hello-from-$(hostname)-$(date -u +%FT%TZ) > /data/test.txt && sleep 3600"]
+      volumeMounts:
+        - name: data
+          mountPath: /data
+  volumes:
+    - name: data
+      persistentVolumeClaim:
+        claimName: nfs-test
+EOF
+kubectl wait --for=condition=Ready pod/nfs-test-pod --timeout=60s
+kubectl exec nfs-test-pod -- cat /data/test.txt
+```
+
+Verify data persists across pod delete/recreate (proves it's NFS-backed, not local emptyDir):
+
+```bash
+kubectl delete pod nfs-test-pod
+kubectl apply -f - <<'EOF'
+apiVersion: v1
+kind: Pod
+metadata:
+  name: nfs-test-pod2
+  namespace: default
+spec:
+  containers:
+    - name: reader
+      image: busybox:1.36
+      command: ["sleep", "3600"]
+      volumeMounts:
+        - name: data
+          mountPath: /data
+  volumes:
+    - name: data
+      persistentVolumeClaim:
+        claimName: nfs-test
+EOF
+kubectl wait --for=condition=Ready pod/nfs-test-pod2 --timeout=60s
+kubectl exec nfs-test-pod2 -- cat /data/test.txt   # same content, different pod
+```
+
+Clean up:
+
+```bash
+kubectl delete pod nfs-test-pod2
 kubectl delete pvc nfs-test
 ```