storage: fix Querier interface documentation

storage/local/interface.go

@@ -73,12 +73,10 @@ type Querier interface {
 	// have no samples in the specified interval from the returned map. In
 	// doubt, specify model.Earliest for from and model.Latest for through.
 	MetricsForLabelMatchers(from, through model.Time, matcherSets ...metric.LabelMatchers) ([]metric.Metric, error)
-	// LastSampleForFingerprint returns the last sample that has been
-	// ingested for the given sets of label matchers. If this instance of the
-	// Storage has never ingested a sample for the provided fingerprint (or
-	// the last ingestion is so long ago that the series has been archived),
-	// ZeroSample is returned. The label matching behavior is the same as in
-	// MetricsForLabelMatchers.
+	// LastSampleForLabelMatchers returns the last sample that has been
+	// ingested for the given sets of label matchers. The label matching
+	// behavior is the same as in MetricsForLabelMatchers.
+	// All returned samples are between the specified cutoff time and now.
 	LastSampleForLabelMatchers(cutoff model.Time, matcherSets ...metric.LabelMatchers) (model.Vector, error)
 	// Get all of the label values that are associated with a given label name.
 	LabelValuesForLabelName(model.LabelName) (model.LabelValues, error)