chore: bump @storybook/addon-docs from 6.2.8 to 6.2.9

Bumps [@storybook/addon-docs](https://github.com/storybookjs/storybook/tree/HEAD/addons/docs) from 6.2.8 to 6.2.9.
- [Release notes](https://github.com/storybookjs/storybook/releases)
- [Changelog](https://github.com/storybookjs/storybook/blob/next/CHANGELOG.md)
- [Commits](https://github.com/storybookjs/storybook/commits/v6.2.9/addons/docs)

Signed-off-by: dependabot[bot] <support@github.com>