Update docs for multiple directory code sniffing

[stevenmc]

Your docs make no mention of being able to CS multiple directories at once, yet this is available in the command line. Please update your ReadMe to demonstrate the following working code:

    //Code sniff the directories Controller, Model, Event and Config
    //Standard below presumes installation of CakePHP coding standard files
    phpcs: {
        application: {
            dir: 'Controller Model Event Config'
        },
        options: {
            bin: 'phpcs',
            standard: 'CakePHP'
        }
    }

[witrin]

See #34 because it offers the default interface for targets. The option dir is very crud.