Add guidance on using profilers from within Jupyter notebooks.

[Robadob]

I've included notebook copies of the two worked examples, but have opted against linking them from the relevant episodes.

Notebook code blocks are marked as py, doesn't appear the markdown engine supports ipynb type.

Closes #23

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[Robadob]

Thanks for the feedback @ns-rse, really useful.

Manually actioned the first, and had to tweak the suggestion for the last. But all were used.