message: fix SubNav docs
diff: @@ -46,7 +46,8 @@ This ensures that the NavLink gets `activeClassName='selected'`
  ```jsx live
  <SubNav aria-label="Main">
  <FilteredSearch>
  - <Dropdown title="Filter">
  + <Dropdown>
  + <Dropdown.Button>Filter</Dropdown.Button>
  <Dropdown.Menu direction="sw">
  <Dropdown.Item>
  <a href="#">Item 1</a>
  