Data directory for mnist1NNdemo.py

[pankajb64]

I apologise if this has already been raised, but examples/mnist1NNdemo.py expects a /Data/MNIST directory with the training data, and I'm not sure where to get this from.

I searched through the backlog and found PR #36, where @Duane321 wanted to add those files but he didn't have the right access.

Please let me know if they're already on the repo and I missed them.

[murphyk]

The data is here.
https://github.com/probml/pmtk3/blob/master/bigData/mnistAll/mnistAll.mat
You can recreate it using
https://github.com/probml/pmtk3/blob/master/bigData/mnistAll/mnistMakeAll.m

[pankajb64]

Thanks!