pull keras & Pytorch from main TOC

Author: sdgilley

articles/machine-learning/toc.yml

@@ -439,10 +439,6 @@
             href: how-to-train-scikit-learn.md
           - name: TensorFlow
             href: how-to-train-tensorflow.md
-          - name: Keras
-            href: how-to-train-keras.md
-          - name: PyTorch
-            href: how-to-train-pytorch.md
           - name: Train with custom Docker image
             href: how-to-train-with-custom-image.md
           - name: Use Key Vault when training