Acceptance criteria

We are adding a new prop for Multiselect (select all) and need to add guidance for this in our docs.

To do

• Start creating content and imagery that will live on the Usage tab of the Dropdown component for the Multiselect (select all) functionality.
• Think about what sections we need to be adding more guidance around this specific feature in the docs.
  • For example: adding guidance in the Content, Interactions, Multiselect, and Modifiers sections would be good places.
• Collect any link references if they helped guide best practices of this feature during the research phase of this umbrella. They can live in the References section if there are any.