Update README.md

[KexinFeng]

Description

Make the snippet code easier to read and attractive to users.

[frankfliu]

Why we remove try-catch?

It's better show real code here. We could improve it like:

    Image img = ImageFactory.getInstance().fromUrl("http://..."); // read image
    try (ZooModel<Image, Classifications> model = criteria.loadModel();
         Predictor<Image, Classifications> predictor = model.newPredictor()) {
         Classifications result = predictor.predict(img);
         // get the classification and probability
         ...
    }