A11y: Fix aria attribute for page number and add correct role

packages/react-experiments/src/components/Pagination/PageNumber.tsx

@@ -14,9 +14,10 @@ export class PageNumber extends React.Component<IPageNumberProps, {}> {
       <DefaultButton
         key={page}
         onClick={this._onClick}
-        aria-selected={selected}
+        aria-checked={selected}
         aria-label={ariaLabel}
         styles={{ root: className }}
+        role="radio"
       >
         {page}
       </DefaultButton>