Merge pull request #222 from SciEvan/master

Update Logistic Regression

docs/source/LogisticRegression.md

@@ -23,9 +23,8 @@ logistic回归通过函数S将ax+b对应到一个隐状态p，p = S(ax+b)，然
 将t换成ax+b，可以得到逻辑回归模型的参数形式：
                                           P(x;a,b) = 1 / (1 + e^(-ax+b))
 
-![image](https://github.com/SciEvan/TensorFlow.NET/tree/master/docs/source/sigmoid.png)
-
-sigmoid函数的图像
+![image](https://github.com/SciEvan/TensorFlow.NET/blob/master/docs/source/sigmoid.png)
+                          sigmoid函数的图像
 
 By the function of the function S, we can limit the output value to the interval [0, 1],
 p(x) can then be used to represent the probability p(y=1|x), the probability that y is divided into 1 group when an x occurs.