message: Migration docs for ModalCloseButton.onClose
  See comments here:
diff: @@ -522,6 +522,10 @@ prop instead.
  - Removed `preserveScrollBarGap` prop. We preserve scroll bar gap by default to
  prevent any layout shift.
  +- `ModalCloseButton` now reads the `onClose` action from the `Modal` context -
  + you no longer need to pass the `onClick` to it. Conversely, the `onClose` prop
  + on `Modal` is now a required prop if you specify `ModalCloseButton`.
  +
  - Only pass `size` values defined in the components theme. Hard-coded values
  will be ignored. Update the styles in `theme.components.Modal` to reflect your
  custom values.
  