The documentation for Enabling Kafka signaling channel says:

To use Kafka signaling to trigger ad hoc incremental snapshots for a connector, you must first enable a source signaling channel in the connector configuration. The source channel implements a watermarking mechanism to deduplicate events that might be captured by an incremental snapshot and then captured again after streaming resumes.

But it doesn't exclude MySQL or explain that MySQL has the option of Ad-hoc read-only incremental snapshots which doesn't require the source signal channel and data collection - it wouldn't work even if it was created since MySQL in read only mode couldn't write to the source signal data collection anyway.

The documentation needs to be clearer that Kafka topic-based signalling only is still a feature of the MySQL Connector.