Add notebooks section on website (#1495)

* Initial infrasctructure for notebooks page

* migrate two notebooks

* add readme notification for notebook dir

* override 'text' prism language to add basic syntactical structure to autogens output

* Rework to retain existing directory and not expose front matter to consumers of the notebook

* improve error handling of process notebooks

* format, ruff and type fixes

* undo changes to navbar

* update readme, CI

* whitespace

* spelling mistakes

* spelling

* Add contributing guide for notebooks

* update notebook

* formatting