Docs: Nit: Fix parquet default compression codec

[tomtongue]

The parquet default compression codec is still gzip in the doc.

I tested the Iceberg 1.4.2 with Spark, and it's zstd from my check:

# DESCRIBE EXTENDED TABLE
...
|Provider                    |iceberg                                                                                                                                                     |       |
|Owner                       |spark                                                                                                                                                       |       |
|Table Properties            |[current-snapshot-id=5229490619909685802,format=iceberg/parquet,format-version=2,write.metadata.compression-codec=gzip,write.parquet.compression-codec=zstd]|       |
+----------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------+-------+

A Parquet file that was written by the Spark app:

$ parquet footer 00000-0-81cf5185-9ecd-424f-9f65-f93a84f3e390-00001.parquet | grep codec | head -1
        "codec" : "ZSTD",

In addition to my check, the following release notes say:
https://iceberg.apache.org/releases/

Use zstd compression for Parquet by default in new tables (#8593)

Confirmed the default compression-codec for the other file formats like avro and orc is correct.

[nastra]

@tomtongue thanks for updating this. Can you please update the PR so that there's a diff only for that one single line that needs the change?

[tomtongue]

@nastra thanks for quickly reviewing this. And sorry for adding unnecessary spaces (I missed they were automatically added by the editor). Remove the spaces.

[nastra]

LGTM, thanks @tomtongue