Update documentation for all changes from cookiecutter modernisation

[HarrisonWilde]

If we merge #207 we need to carry out updates to the docs to reflect this, particularly in structure.md.

[caldwellst]

Same goes for updating the style guidance if we merge #204, depending on our decisions, so the style guide is more prescriptive than descriptive. Same applies to the laptop setup guide depending on our tech choices in #207 and others. I might leave this issue as one to review all of our documentation once we've merged the recent PRs in the cookiecutter.

[HarrisonWilde]

Ok good point, I will edit the title to reflect this