Fix buffer size property name in sample configurations

All the sample configuration files refer to `bufferSizeByteLimit` while the correct property name is `bufferByteSizeLimit`, [as you can see here](https://github.com/awslabs/amazon-kinesis-connectors/blob/master/src/main/java/com/amazonaws/services/kinesis/connectors/KinesisConnectorConfiguration.java#L71).

This had me scratching my head for a long while, as size limits had no effect in actual use (record count and millisecond work fine!)