GAN_mnist: fix `generator` return doc
GAN_mnist: fix `generator` return doc

Remove `logits` from return doc, since it isn't actually returned.
msanterre/deep_learning,yuvrajsingh86/DeepLearning_Udacity,udacity/deep-learning,Bismarrck/deep-learning,adrianstaniec/deep-learning,gatmeh/Udacity-deep-learning,d-k-b/udacity-deep-learning,zizouvb/deeplearning,gatmeh/Udacity-deep-learning,mkowoods/deep-learning,0x4a50/udacity-0x4a50-deep-learning-nanodegree,georgebastille/deep-learning,Bismarrck/deep-learning,ktmud/deep-learning,rishizek/deep-learning,kolaogun/deep-learning,brandoncgay/deep-learning,ktmud/deep-learning,adrianstaniec/deep-learning,samirma/deep-learning,oscarmore2/deep-learning-study,kiritisai/deep-learning-udacity,brandoncgay/deep-learning,d-k-b/udacity-deep-learning,fnakashima/deep-learning,oscarmore2/deep-learning-study,abhi1509/deep-learning,oscarmore2/deep-learning-study,lukechen526/deep-learning,voyageth/udacity-Deep_Learning_Foundations_Nanodegree,lukechen526/deep-learning,0x4a50/udacity-0x4a50-deep-learning-nanodegree,voyageth/udacity-Deep_Learning_Foundations_Nanodegree,JavascriptMick/deeplearning,quietcoolwu/deep-learning,scottquiring/Udacity_Deeplearning,scottquiring/Udacity_Deeplearning,abhi1509/deep-learning,gururajl/deep-learning,rishizek/deep-learning,samirma/deep-learning,hdchan/deep-learning