Add safeguard related statements for max_backoff setting (#7889)

filebeat/docs/inputs/input-common-file-options.asciidoc

@@ -348,9 +348,10 @@ specifying 10s for `max_backoff` means that, at the worst, a new line could be
 added to the log file if {beatname_uc} has backed off multiple times. The
 default is 10s.
 
-Requirement: max_backoff should always be set to `max_backoff <=
-scan_frequency`. In case `max_backoff` should be bigger, it is recommended to
-close the file handler instead let the {beatname_uc} pick up the file again.
+Requirement: Set `max_backoff` to be greater than or equal to `backoff` and
+less than or equal to `scan_frequency` (`backoff <= max_backoff <= scan_frequency`).
+If `max_backoff` needs to be higher, it is recommended to close the file handler
+instead and let {beatname_uc} pick up the file again.
 
 [float]
 ===== `backoff_factor`