message: Add a link to KL divergence
diff: @@ -671,6 +671,8 @@ class KLDivergence(LossFunctionWrapper):
  `loss = y_true * log(y_true / y_pred)`
  + See: https://en.wikipedia.org/wiki/Kullback%E2%80%93Leibler_divergence
  +
  Usage:
  ```python
  