Bump badge to beta version (#5048)

Author: LFDanLu

packages/@react-spectrum/menu/docs/Menu.mdx

@@ -289,7 +289,7 @@ import {Keyboard, Text} from '@react-spectrum/text';
 </MenuTrigger>
 ```
 
-## Unavailable Items <VersionBadge version="alpha" style={{marginLeft: 4, verticalAlign: 'bottom'}} />
+## Unavailable Items <VersionBadge version="beta" style={{marginLeft: 4, verticalAlign: 'bottom'}} />
 
 ContextualHelpTrigger disables a menu item's action and replaces it with a popover with information on why the item is unavailable and may link users to more information elsewhere.