Add distinct section names for PyTorch and TF
Super-small fix here - the section names for PyTorch and TF were identical in the notebooks doc, which meant that when you clicked on one of the TF categories in the TOC you got sent to the PyTorch one instead (because it came first).

This PR adds separate section names so this doesn't happen! (Thanks @mishig25 for telling me how to do that!)
_The documentation is not available anymore as the PR was closed or merged._<|||||>Thank you for fixing this!