[Dropdown] add more guidance for the inline modifier

[laurenmrice]

Update inline dropdown modifier guidance

• We currently have some guidance on the inline dropdown modifier, but we should be more specific in what situations do we use inline dropdowns? What are the specific use cases we can call out here to guide people a little more.

---

Guidance to add

• Add some brief guidance that we do not use inline dropdowns for filtering a menu of options (like we do for combobox or filterable multi-select). If we tried to do that with inline dropdowns there would be too much visual interactivity with the width of the dropdown container constantly adapting to the new text you are typing in the field and the open menu beneath the field is either removing items from the list or jumping to different items that are relevant to the filter. This could be visually distracting/confusing.
• Show a do/don't image example of the width of an inline dropdown menu. Something like the image example below. We do not want to restrict the width of the menu to fit the field container width based on the length of the user's current selection. This can sometimes truncate the text of nearly all items in the dropdown menu. Instead, the menu can be longer in width than the field container.