document the ember-cli-storybook option now that it's opt-in
document the ember-cli-storybook option now that it's opt-in

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