Include updates to Kafka output documentation

libbeat/outputs/kafka/docs/kafka.asciidoc

@@ -44,7 +44,7 @@ endif::[]
 ==== Compatibility
 
 This output can connect to Kafka version 0.8.2.0 and later. Older versions
-might work as well, but are not supported.
+might work as well, but are not supported. When using Kafka 4.0 and newer, the version must be set to at least `"2.1.0"`
 
 ==== Configuration options
 
@@ -69,7 +69,7 @@ The cluster metadata contain the actual Kafka brokers events are published to.
 
 ===== `version`
 
-Kafka protocol version that {beatname_uc} will request when connecting. Defaults to 1.0.0.
+Kafka protocol version that {beatname_uc} will request when connecting. Defaults to 1.0.0. When using Kafka 4.0 and newer, the version must be set to at least `"2.1.0"`
 
 Valid values are all kafka releases in between `0.8.2.0` and `2.6.0`.
 
@@ -300,7 +300,7 @@ The keep-alive period for an active network connection. If 0s, keep-alives are d
 
 ===== `compression`
 
-Sets the output compression codec. Must be one of `none`, `snappy`, `lz4`, `gzip` and `zstd`. The default is `gzip`.
+Sets the output compression codec. Must be one of `none`, `snappy`, `lz4` and `gzip`. The default is `gzip`.
 
 [IMPORTANT]
 .Known issue with Azure Event Hub for Kafka