[Filebeat]add compatibility information to kafka input

[TomonoriSoejima]

Describe the enhancement:

Current doc https://www.elastic.co/guide/en/beats/filebeat/7.5/filebeat-input-kafka.html may warrant compatibility information such as below.
Below exists in kafka output but not in kafka input

Compatibility
This output works with all Kafka versions in between 0.11 and 2.1.0. Older versions might work as well, but are not supported.

I tracked sarama library is used in both input and output, but I could not determine if they are using the same version.

[jsoriano]

@TomonoriSoejima in principle same versions are supported in kafka input and output, but it is true that it should be documented in both places. Thanks for reporting!