.md documentation out of date

Documentation examples refer to CsvFile:: which doesn't appear to exist.

$csvFile = new \Keboola\Csv\CsvFile(
    $fileName,
    CsvFile::DEFAULT_DELIMITER,
    CsvFile::DEFAULT_ENCLOSURE,
    CsvFile::DEFAULT_ESCAPED_BY,
    1 )

I figured it out after a bit of tail chasing, but I think the reference to CsvFile should be CsvReader now.

Otherwise, so far so good! Nice library! :-)