docs: Note pyiceberg only works with datafusion < 49

[Datafusion >= 49 is not backward compatible](apache/iceberg-rust#1647 (comment))

Author: manuzhang

mkdocs/docs/api.md

@@ -1939,7 +1939,7 @@ PyIceberg integrates with [Apache DataFusion](https://datafusion.apache.org/) th
 
     The integration has a few caveats:
 
-    - Only works with `datafusion >= 45`
+    - Only works with `datafusion >= 45, < 49`
     - Depends directly on `iceberg-rust` instead of PyIceberg's implementation
     - Has limited features compared to the full PyIceberg API
 

mkdocs/docs/index.md

@@ -62,7 +62,7 @@ You can mix and match optional dependencies depending on your needs:
 | gcsfs         | GCSFS as a FileIO implementation to interact with the object store        |
 | rest-sigv4    | Support for generating AWS SIGv4 authentication headers for REST Catalogs |
 | pyiceberg-core | Installs iceberg-rust powered core                                       |
-| datafusion    | Installs both PyArrow and Apache DataFusion                               | 
+| datafusion    | Installs both PyArrow and Apache DataFusion                               |
 
 You either need to install `s3fs`, `adlfs`, `gcsfs`, or `pyarrow` to be able to fetch files from an object store.