Missing aria-modal=true attribute

[gnoyixiang]

Hello, based on the W3 documentation on dialogs, it is stated that

The dialog container element has aria-modal set to true.

I see this in other react accessibility based libraries such as ReachUI and Reakit. Am hoping that the attribute [aria-modal=true] can be added in.

https://www.w3.org/TR/wai-aria-practices-1.2/#dialog_roles_states_props