[Request] Show instructions for `multiselect` and `groupMultiselect`

[bluwy]

Is your feature request related to a problem? Please describe.
We had reports that it's unclear how to select items (changesets/changesets#255)

Describe the solution you'd like
It'd be nice to show instructions for selecting for multiselect and groupMultiselect, similar to autocomplete and autocompleteMultiselect today:

Maybe this could be under an option whether to show by default.

Describe alternatives you've considered
#551 is a similar issue of a more general footer option instead of like an instructions: boolean option

Additional context
n/a

[43081j]

makes sense to me 👍

to avoid a breaking change, i agree we need an option defaulted to off