message: fix exports in doc-components
diff: @@ -3,3 +3,6 @@ export {default as MergeBox} from './MergeBox'
  export {default as MergeButton} from './MergeButton'
  export {default as MergeDetail} from './MergeDetail'
  export {default as ExampleHeading} from './ExampleHeading'
  +export {default as Header} from './Header'
  +export {default as SideNav} from './SideNav'
  +export {default as customTheme} from './theme'
  