Missing microbatch documentation for iceberg in dbt-athena

### Contributions

- [x] I have read the contribution docs, and understand what's expected of me.

### Link to the page on docs.getdbt.com requiring updates

https://docs.getdbt.com/reference/resource-configs/athena-configs

### What part(s) of the page would you like to see updated?

I see microbatch was added to dbt-athena (and iceberg specifically) in https://github.com/dbt-labs/dbt-adapters/issues/409

So I would imagine those two parts need to be updated:
1. https://docs.getdbt.com/reference/resource-configs/athena-configs#incremental-models
2. https://docs.getdbt.com/reference/resource-configs/athena-configs#iceberg

### Additional information

_No response_