fix: scan file buff size

internal/opt/var.go

@@ -7,4 +7,7 @@ const (
 var (
 	Debug   bool
 	Timeout int
+
+	BuffSize    = 5 * 1024 * 1024   // 5M
+	MaxBuffSize = 100 * 1024 * 1024 // 100M, default elastic_search doc max size
 )