Fix secrets docs in 1.12 branch (#10056)

* Fix secrets docs

* Update secret.md

content/en/docs/concepts/configuration/secret.md

@@ -339,9 +339,15 @@ files.
 
 When a secret being already consumed in a volume is updated, projected keys are eventually updated as well.
 Kubelet is checking whether the mounted secret is fresh on every periodic sync.
-However, it is using its local ttl-based cache for getting the current value of the secret.
-As a result, the total delay from the moment when the secret is updated to the moment when new keys are
-projected to the pod can be as long as kubelet sync period + ttl of secrets cache in kubelet.
+However, it is using its local cache for getting the current value of the Secret.
+The type of the cache is configurable using the  (`ConfigMapAndSecretChangeDetectionStrategy` field in
+[KubeletConfiguration struct](https://github.com/kubernetes/kubernetes/blob/{{< param "docsbranch" >}}/pkg/kubelet/apis/kubeletconfig/v1beta1/types.go)).
+It can be either propagated via watch (default), ttl-based, or simply redirecting
+all requests to directly kube-apiserver.
+As a result, the total delay from the moment when the Secret is updated to the moment
+when new keys are projected to the Pod can be as long as kubelet sync period + cache
+propagation delay, where cache propagation delay depends on the chosen cache type
+(it equals to watch propagation delay, ttl of cache, or zero corespondingly).
 
 {{< note >}}
 **Note:** A container using a Secret as a