Correct the misdescription of LogSoftmax class

Correct the misdescription comment of LogSoftmax class from 'softmax loss function' to 'logarithm of softmax'

example/bayesian-methods/bdk_demo.py

@@ -58,7 +58,7 @@ def backward(self, out_grad, in_data, out_data, in_grad):
 
 
 class LogSoftmax(mx.operator.NumpyOp):
-    """Generate helper functions to evaluate softmax loss function"""
+    """Generate helper functions to calculate the logarithm of softmax"""
     def __init__(self):
         super(LogSoftmax, self).__init__(False)