Reorganise and update the writing guide

[mwermelinger]

• [x] add the linter configuration after closing #19
• [ ] break into separate sections that can be linked from templates
• [x] change sections with code to notebook format
• [x] mention in the example essays that Colab also doesn't require software

[mwermelinger]

While the guide hasn't been split into individual sections, the templates link to them, so this can be considered done.