[Docs]: Dropdown order implementation

[Shrinks99]

Over the next month I'd like to start documenting some of our front-end decisions where much of the thinking behind them only exists in my head. This is an unscalable practice, but also just generally a bad one! I can't be the arbitor of consistency through made up rules forever 🙃

@emma-sg and I thought dropdowns might be a good place to start .

- Actions related only to the current page (remove from collection)
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- Actions related to editing the object
- Other actions related to the current object
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- Actions related to exporting/downloading
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- Copy information to clipboard
- Copy IDs to clipboard
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- Destructive actions

Other relevant things to document

Will split these out into separate issues later once / if this issue is closed:

• Status icons and their meanings (see figma)
• Use of colour throughout the app