Update README.md

The component is not exported as default, so when importing, you need to use curly braces

Author: pakman198

README.md

@@ -31,6 +31,7 @@ Following plain React Bootstrap component
 ```
 becomes
 ```js
+import { LinkContainer } from 'react-router-bootstrap'
 <LinkContainer to="/foo/bar">
   <Button>Foo</Button>
 </LinkContainer>