add comment for HTTPTIMEOUT constant

etcd.go

@@ -91,6 +91,8 @@ const (
 	ELECTIONTIMTOUT  = 200 * time.Millisecond
 	HEARTBEATTIMEOUT = 50 * time.Millisecond
 	// Timeout for internal raft http connection
+	// The origin timeout for http is 45 seconds 
+	// which is too long for our usage.
  	HTTPTIMEOUT      = time.Second
 )