Fixed statement about logging unknown scopes

I just setup a simple test enviornment and could confirm this.
But please soneone with some more insight should verify this.

My config:
```` php
// Default debug logger
CakeLog::config('debug', array(
	'engine' => 'File',
	'types' => array('notice', 'info', 'debug'),
	'file' => 'debug',
));
// Default error logger
CakeLog::config('error', array(
	'engine' => 'File',
	'types' => array('warning', 'error', 'critical', 'alert', 'emergency'),
	'file' => 'error',
));

// Custom logger for a single scope
CakeLog::config('scoped', array(
		'engine' => 'File',
		'scopes' => array('known-scope'),
		'types' => array('warning', 'error'),
		'file' => 'scoped'
	)
);
````

My warnings
```` php
CakeLog::warning('this is a normal warning');
CakeLog::warning('this is a known scoped warning', 'known-scope');
CakeLog::warning('this is an unknown scoped warning', 'foo');
````
error.log
````
2014-08-07 01:06:31 Warning: this is a normal warning
2014-08-07 01:06:31 Warning: this is a known scoped warning
2014-08-07 01:06:31 Warning: this is an unknown scoped warning
````

scoped.log
````
2014-08-07 01:06:31 Warning: this is a known scoped warning
````