Update Kafka Output settings documentation to indicate minimum versio…

…n value for Kafka 4.0 (#1445)

docs/en/ingest-management/fleet/fleet-settings-output-kafka.asciidoc

@@ -19,7 +19,7 @@ NOTE: If you plan to use {ls} to modify {agent} output data before it's sent to
 | The Kafka protocol version that {agent} will request when connecting. 
 Defaults to `1.0.0`.
 Currently Kafka versions from `0.8.2.0` to `2.6.0` are supported, however the latest 
-Kafka version (`3.x.x`) is expected to be compatible when version `2.6.0` is selected.
+Kafka version (`3.x.x`) is expected to be compatible when version `2.6.0` is selected. When using Kafka 4.0 and newer, the version must be set to at least `2.1.0`.
 
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