added equations that describe neural network

Author: Quinn Liu

imagesForExplanation/NeuralNetworkEquations.jpg

@@ -27,4 +27,6 @@ Neural Networks
 
     + where (a_i)^(j) = activation of unit i in layer j and BigTheta^(j) = matrix of weights controlling function mapping from layer j to layer j + 1
       - The dimension of BigTheta^(j) is s_j+1 x (s_j + 1) if a neural network has s_j units in layer j & s_j+1 units in layer j + 1.
+      - This is the set of equations that describes the above neural network configuration:
+      ![alt text](https://raw.github.com/quinnliu/MachineLearning/master/imagesForExplanation/NeuralNetworkExample.jpg)