Isabel new branch cookbook stuff

i added the following files: to features: -custom_toc.md -custom_download.md -h5p_examples.md -theory_questions.md -live_code.md

to examples:

• interactive_templates.md
• example_gumbel.ipynb
• example_quiz_interactive.ipynb
• parametric_questions.ipynb

I got errors for: -interactive_element.ipynb -coding_theory_widgets.ipynb

• interactive-wave.ipynb
• jupiterlite-gallery.md I deleted them for now just until i worked the error out.