Fix typings for addon-backgrounds
Fix typings for addon-backgrounds

storybooks/storybook,storybooks/react-storybook,storybooks/storybook,storybooks/react-storybook,kadirahq/react-storybook,storybooks/react-storybook,storybooks/storybook,storybooks/react-storybook,storybooks/storybook,storybooks/storybook,kadirahq/react-storybook,storybooks/storybook,storybooks/storybook