Fix comment error of the struct 'UserDefinedMetric'

pkg/kubelet/apis/stats/v1alpha1/types.go

@@ -324,7 +324,7 @@ type UserDefinedMetricDescriptor struct {
 	Labels map[string]string `json:"labels,omitempty"`
 }
 
-// UserDefinedMetric represents a metric defined and generate by users.
+// UserDefinedMetric represents a metric defined and generated by users.
 type UserDefinedMetric struct {
 	UserDefinedMetricDescriptor `json:",inline"`
 	// The time at which these stats were updated.