Update README.md

README.md

@@ -102,7 +102,7 @@ which need to completed using only the `numpy` package and the `correlate` or `c
 
 ### 3. Complete cnn.py
 
-`cnnbp.py` includes the following subroutine
+`cnn.py` includes the following subroutine
 
 ```python
 def trainCNN(X, Y, **args):