minor update doc

Author: chen0040

README.md

@@ -104,7 +104,7 @@ curl -H 'Content-Type: application/json' -X POST -d '{"level":"word-glove", "sen
 * Step 1: Change tensorflow to tensorflow-gpu in requirements.txt and install tensorflow-gpu
 * Step 2: Download and install the [CUDA® Toolkit 9.0](https://developer.nvidia.com/cuda-90-download-archive) (Please note that
 currently CUDA® Toolkit 9.1 is not yet supported by tensorflow, therefore you should download CUDA® Toolkit 9.0)
-* Step 3: Download and unzip the [cuDNN 7.4 for CUDA@ Toolkit 9.0](https://developer.nvidia.com/cudnn) and add the
+* Step 3: Download and unzip the [cuDNN 7.0.4 for CUDA@ Toolkit 9.0](https://developer.nvidia.com/cudnn) and add the
 bin folder of the unzipped directory to the $PATH of your Windows environment 
 
 # TODO