[Java][Docs] Document the use of the batchSize argument in Dataset ScanOptions

Several ScanOptions methods take a batchSize argument as shown: 

`public ScanOptions(long batchSize) {`
`    this(batchSize, Optional.empty());`
``}

Since the scanner reads one ArrowRecordBatch per load invocation, setting the parameter to a size larger than the RecordBatch has no effect. It only works when it's smaller than the number of rows in the RecordBatch, (i.e., the number or records read is equal to min(batchSize, recordBatch rowCount), potentially leading to some confusion. 

**Reporter**: [Larry White](https://issues.apache.org/jira/browse/ARROW-17346) / @lwhite1

_{**Note**: *This issue was originally created as [ARROW-17346](https://issues.apache.org/jira/browse/ARROW-17346). Please see the [migration documentation](https://github.com/apache/arrow/issues/14542) for further details.*}

Comienza con los métodos de Dataset ScanOptions que aceptan batchSize y sigue cómo el escáner carga un ArrowRecordBatch por invocación. Documenta que los valores mayores que el recuento de filas de RecordBatch no tienen ningún efecto adicional, mientras que los valores menores limitan los registros a min(batchSize, recordBatch rowCount); se considera terminado cuando la documentación de ScanOptions deja claro este comportamiento.

Escrito por el modelo de indexación a partir del texto del issue.