Revise definition of aria-multiselectable to be consistent with normative statements related to aria-checked

[mcking65]

Describe the change

The aria-multiselectable property Does not mention that aria-checked can be used to represent selection.

Revise the definition language or add a note to ensure readers understand that aria-multiselectable should be used on widgets that use aria-checked to represent selection.

Link to the version of the specification or documentation you were looking at

Link to documentation: https://w3c.github.io/aria/#aria-multiselectable

Does the issue exists in the editors draft (the editors draft is the most recent draft of the specification)?

Yes