Delete the wrong comment about CertDirectory of kubelet

The default value of CertDirectory was changed to /var/lib/kubelet/pki.

Author: tnqn

cmd/kubelet/app/options/options.go

@@ -85,9 +85,8 @@ type KubeletFlags struct {
 	// Container-runtime-specific options.
 	config.ContainerRuntimeOptions
 
-	// certDirectory is the directory where the TLS certs are located (by
-	// default /var/run/kubernetes). If tlsCertFile and tlsPrivateKeyFile
-	// are provided, this flag will be ignored.
+	// certDirectory is the directory where the TLS certs are located.
+	// If tlsCertFile and tlsPrivateKeyFile are provided, this flag will be ignored.
 	CertDirectory string
 
 	// cloudProvider is the provider for cloud services.