Add docs for reading iceberg tables

We don't have any docs on how to read Iceberg tables into Sedona. The Iceberg can be hosted anywhere, either in the Glue catalog or the Unity catalog.

Things to add:
1. Configuration to set up to connect to catalogs (glue or unity). Either is fine as a starting point.
2. Examples on how to read Iceberg tables once it is connected, with this syntax:
```
sedona.read.format("iceberg").load("catalog_name.schema_name.table_name")
```