Update README.md

Author: joaopauloschuler

examples/VisualGAN/README.md

@@ -1,2 +1,28 @@
 # Artificial Art Example
-<img src="https://github.com/joaopauloschuler/neural-api/blob/master/docs/art2.jpg" height="400">
+<img src="https://github.com/joaopauloschuler/neural-api/blob/master/docs/art2.jpg" height="400"></img>
+
+In this example, 2 neural networks will enter an arms race via a [Generative Adversarial Neural Network](https://en.wikipedia.org/wiki/Generative_adversarial_network): `FGenerative` and `FDiscriminator`. The Generative network will learn how to create images while the discriminator will compare these images against the CIFAR-10 dataset.
+
+The discriminator `FDiscriminator` is trained via `TNeuralDataLoadingFit`:
+```
+  FFit.OnAfterEpoch := @Self.DiscriminatorOnAfterEpoch;
+  FFit.OnAfterStep := @Self.DiscriminatorOnAfterStep;
+  FFit.OnStart := @Self.DiscriminatorOnStart;
+  FFit.DataAugmentationFn := @Self.DiscriminatorAugmentation;
+  ...
+  {$ifdef OpenCL}
+  if FHasOpenCL then
+  begin
+    FFit.EnableOpenCL(FEasyOpenCL.PlatformIds[0], FEasyOpenCL.Devices[0]);
+    Generative.EnableOpenCL(FEasyOpenCL.PlatformIds[0], FEasyOpenCL.Devices[0]);
+  end;
+  {$endif}
+  //FFit.FitLoading(FDiscriminator, 64*10, 500, 500, 64, 35000, @GetDiscriminatorTrainingPair, nil, nil); // This line does the same as below
+  FFit.FitLoading(FDiscriminator, 64*10, 500, 500, 64, 35000, @GetDiscriminatorTrainingProc, nil, nil); // This line does the same as above
+```
+
+From the above code, some events are used and are interesting to note:
+* `FFit.OnStart := @Self.DiscriminatorOnStart;` is responsible for building required memory structures.
+* `FFit.OnAfterEpoch := @Self.DiscriminatorOnAfterEpoch;` calls the generative training. Therefore, the generative training is done after each discriminator epoch.
+
+In order to show how `TNeuralDataLoadingFit` loads training data, above implementation has 2 equivalent calls (the first is commented) with both `GetDiscriminatorTrainingPair` and `GetDiscriminatorTrainingProc`.