[BUG] Inconsistent hyperlinks for the "back" button in (at least) QML demos

[emgilfuster]

Inconsistent hyperlinks for the "back" button in (at least) QML demos

The back button at the top left of the demo page has different hyperlinks for different demos in the qml list.

• Expected behavior: the back button from all qml demos is hyperlinked to https://pennylane.ai/qml/demos_qml.html

• Actual behavior: for some demos, including https://pennylane.ai/qml/demos/tutorial_tn_circuits.html (but it's not the only one), the back button is hyperlinked to https://pennylane.ai/qml/index.html

[CatalinaAlbornoz]

Thanks for opening this issue!

[josh146]

Thanks @emgilfuster! This is because tutorial_tn_circuits is not listed in the ToC for the demos_qml.rst page:

https://github.com/PennyLaneAI/qml/blame/master/demos_qml.rst#L134-L153

We should probably go through and audit, and ensure that all demos are listed in the table of contents for the correct categories.

[KetpuntoG]

problem solved, demos are now up to date :)