Add new recipes created by Nuffield Research Placement students

[sadielbartholomew]

We have around six new entries for our 'Recipes' section of the documentation, created by our two Nuffield Research Placement students, Natalia and George. These should be added to the documentation. @bewithankit has kindly agreed to review them before they are added.

I will aim to get the PRs up for this early (or middle of) next week. I think it is best to add each recipe as a separate PR so that we can keep them self-contained for reviewing, but if you prefer otherwise please let me know, @bewithankit.

[sadielbartholomew]

This was completed a while back - see #818, #819, #820, #821 and #822, so belatedly closing.