Update label_strategy.go

metrics/label_strategy.go

@@ -2,7 +2,11 @@ package metrics
 
 import "github.com/czerwonk/bird_exporter/protocol"
 
+// LabelStrategy abstracts the label generation for protocol metrics
 type LabelStrategy interface {
+	// LabelNames is the list of label names
 	LabelNames() []string
+	
+	// Label values is the list of values for the labels specified in `LabelNames()` 
 	LabelValues(p *protocol.Protocol) []string
 }