Update Iceberg Docs

[guillesd]

Added:

• Supported functionality when attaching iceberg catalogs
• Unsupported functionality
• Interoperability with DuckLake

[guillesd]

@Tmonster @Tishj could you please check? Also how do we expose querying old snapshot ids when the catalog is attached (I know the iceberg_scan exposes this, so what is the syntax?)

[Tmonster]

Syntax for querying old snapshots is like this
from my_datalake.default.filtering_on_bounds AT (VERSION <shapshot_id>). To get the metadata information you can just call the iceberg_snapshots function directly on a table

select * from iceberg_snapshots(my_datalake.default.table1);
select * from my_datalake.default.table1 AT (VERSION => <snapshot_id>;

It's not the most intuitive. I have a ticket open to query sequence number https://github.com/duckdblabs/duckdb-internal/issues/5740

[Tmonster]

Thanks!
A couple of comments