Add a comment to the adaptive range limit comment

pager.go

@@ -32,7 +32,7 @@ type pager struct {
 }
 
 func addLimitTokenString(w io.Writer, limit int, token string) {
-	if limit == -1 || limit > 0 {
+	if limit == AdaptiveRangeLimit || limit > 0 {
 		fmt.Fprintf(w, " limit %d", limit)
 	}
 	if token != "" {

range.go

@@ -31,6 +31,10 @@ import (
 )
 
 const (
+	// AdaptiveRangeLimit is a sentinel value that is used to indicate an intent
+	// to range over data in a partition as fast as possible. The server will
+	// determine an appropriate limit to use to range over the partition as fast
+	// as possible while ensuring the server remains healthy.
 	AdaptiveRangeLimit = -1
 )