Add alternative method for creating RecordBatchReader from Arrow C stream

Author: kosiew

python/tests/test_dataframe.py

@@ -1654,6 +1654,8 @@ def test_arrow_c_stream_to_table_and_reader(fail_collect):
     assert table.column("a").num_chunks == 2
 
     reader = pa.RecordBatchReader._import_from_c_capsule(df.__arrow_c_stream__())
+    # alternatively, we could use
+    # reader = pa.RecordBatchReader.from_stream(df)
     assert isinstance(reader, pa.RecordBatchReader)
     reader_table = pa.Table.from_batches(reader)
     expected = pa.Table.from_batches([batch1, batch2])