Update README.md #128

README.md

@@ -93,7 +93,12 @@ luarocks install lua-csnappy
 luarocks install md5
 luarocks install uuid
 luarocks install csvigo
-PREFIX=$HOME/torch/install luarocks install turbo # if you need to use web application
+
+# if you need to use web application
+PREFIX=$HOME/torch/install luarocks install turbo
+
+# if you need to use cuDNN library. cuDNN is required.
+luarocks install cudnn
 ```
 
 #### Getting waifu2x