docs(MIGRATION): update hierarchy separator section
docs(MIGRATION): update hierarchy separator section

Updated the command to work in any scenario and added a note about mdx.
storybooks/react-storybook,storybooks/storybook,storybooks/storybook,storybooks/react-storybook,storybooks/react-storybook,storybooks/storybook,storybooks/react-storybook,storybooks/storybook,storybooks/storybook,storybooks/storybook,kadirahq/react-storybook,kadirahq/react-storybook,storybooks/storybook