Update the CTR image and description.

The new image is a courtesy of Varun

ctr/README.md

@@ -120,7 +120,7 @@ The model structure is as follows:
 Figure 2. Wide & Deep Model
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-The wide part of the left side of the model can accommodate large-scale coefficient features and has some memory for some specific information (such as ID); and the Deep part of the right side of the model can learn the implicit relationship between features.
+The wide part of the top side of the model can accommodate large-scale coefficient features and has some memory for some specific information (such as ID); and the Deep part of the bottom side of the model can learn the implicit relationship between features.
 
 
 ### Model Input