docs(kafka_franz): metadata_max_age add a note about relation to regexp

[krynju]

To give a hint about how to set up endless processing of kafka topics with regexp #3578

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[mmatczuk]

@krynju please note that the docs here are auto generated - you shall be adding content to

connect/internal/impl/kafka/franz_client.go

Line 55 in 087bb66

Description("The maximum age of metadata before it is refreshed.").