FMWK-644-udf-index-backup-xdr

- added comment

porcessor_file_reader.go

@@ -157,6 +157,8 @@ func newEncryptionReader(
 // distributeFiles is only used for asbx restore, to follow the order of files.
 // All files myst be sorted with util.SortBackupFiles first.
 // Then they will be distributed over workers according to its prefix and in order according to its suffix.
+// Valid file name: <prefix>_<namespace>_<suffix>.asbx
+// Example: 4_source-ns1_47.asbx
 func distributeFiles(input chan models.File, output []chan models.File, errors chan<- error) {
 	if len(output) == 0 {
 		errors <- fmt.Errorf("failed to distibute files to 0 channels")