docs: update data sources documentation to include support for Python objects implementing __arrow_c_stream__ protocol

Author: kosiew

docs/source/user-guide/data-sources.rst

@@ -158,7 +158,12 @@ as Delta Lake. This will require a recent version of
     df = ctx.table("my_delta_table")
     df.show()
 
-On older versions of ``deltalake`` (prior to 0.22) you can use the 
+Any Python object that implements the
+``__arrow_c_stream__`` protocol can be registered with
+``register_dataset``. This includes scanners from libraries such as
+``nanoarrow``, ``Polars``, or ``DuckDB``.
+
+On older versions of ``deltalake`` (prior to 0.22) you can use the
 `Arrow DataSet <https://arrow.apache.org/docs/python/generated/pyarrow.dataset.Dataset.html>`_
 interface to import to DataFusion, but this does not support features such as filter push down
 which can lead to a significant performance difference.