Merge pull request #24863 from povsister/signing-duration

Fix experimental flag example

Author: k8s-ci-robot

content/en/docs/reference/command-line-tools-reference/kubelet-tls-bootstrapping.md

@@ -243,7 +243,7 @@ for example:
 The validity duration of signed certificates can be configured with flag:
 
 ```
---experimental-cluster-signing-duration
+--cluster-signing-duration
 ```
 
 ### Approval