Update 2014-09-26-The-Exceptional-Doorway.md

Minor edits, and added example of deeply nested closure error handling.
The other style I've seen in JS-land is accepting two closures, one for the error scenario, one for success. Is that worth discussing or does it just distract from the point?

    database.findDataMatching('query', function(error) {
        handleError(error);
    }, function(result){
        processTheResult(result);
    });

This looks more similar to the Promise format below, but it does still add to rightward-drift when nested.