Add Iceberg documentation to website

[timsaucer]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

I believe we can now access Iceberg tables via ffi according to @kevinjqliu 's recent work. It would be good to update our online documentation to reflect this.

Describe the solution you'd like

Description of how to use iceberg tables or a link to the appropriate documentation on their site.

[kevinjqliu]

Yep! i plan to add it in https://datafusion.apache.org/python/user-guide/data-sources.html#iceberg

The Iceberg FFI is currently in the "pyiceberg_core" package, which is the iceberg-rust python bindings we expose for pyiceberg. I plan to release pyiceberg with the new FFI (in the next release, 0.10.0) and then add an example with pyiceberg.