cuDNN missing from installer

I recently updated tensorflow which seems to require a cudnn64_6.dll now.
I only had a cudnn64_5.dll at C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v8.0\bin so I thought it would be a good idea to update. I now have a C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v9.0\bin directory, but there is no cudnn dll in it at all. The installer cuda_9.0.176_windows_network.exe did not list cuDNN as a library option to install either.

GPU is a GeForce 840M.
Operating system is Windows 8.1, 64-bit.
Driver version is 385.54.

I found that after registering for this stupid account bullshit here, I can download the dll separately from:

https://developer.nvidia.com/rdp/cudnn-download

It does not list Windows 8.1, but overwriting the files in C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v8.0\ with their corresponding counterpart in cudnn-8.0-windows7-x64-v6.0.zip worked for me.

CUDNN is not included as part of the CUDA toolkit download/install. It requires a separate download.

could you please provide the appropriate link?