docs: updated isolation.level description

[avaamsel]

Updated the description for isolation.level in Kafka ingestion docs.

This PR has:

• [x ] been self-reviewed.

[FrankChen021]

I have reviewed the code for correctness, edge cases, concurrency, and integration risks; no issues found.

Reviewed 2 of 2 changed files.

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This is an automated review by Codex GPT-5.5

[317brian]

minor nit

[317brian]

Suggested change

The `isolation.level` property determines how Druid handles transactional Kafka messages. Although standard Kafka consumers default to `read_uncommitted`, Druid's ingestion engine defaults `read_committed`. This ensures that only finalized data is indexed and aborted transactions are ignored. If you need to use legacy Kafka brokers or don’t want Druid to consume only committed transactions, explicitly set `isolation.level` to `read_uncommitted`. Note that using `read_uncommitted` removes Druid's offset gap check, which requires the message source to ensure the message offsets are continuous.

The `isolation.level` property determines how Druid handles transactional Kafka messages. Although standard Kafka consumers default to `read_uncommitted`, Druid's ingestion engine defaults to `read_committed`. This ensures that only finalized data is indexed and aborted transactions are ignored. If you need to use legacy Kafka brokers or don’t want Druid to consume only committed transactions, explicitly set `isolation.level` to `read_uncommitted`. Note that using `read_uncommitted` removes Druid's offset gap check, which requires the message source to ensure the message offsets are continuous.