`<InputGroup />` component example:

```js
import {
  InputGroup,
  Input,
  InputGroupAddon,
  InputGroupButton,
} from '$PACKAGE_NAME';

<InputGroup>
  <Input placeholder="username" />
  <InputGroupAddon>
    <Input addon type="checkbox" />
  </InputGroupAddon>
  <Input placeholder="Check it out" />
  <InputGroupButton>Send</InputGroupButton>
</InputGroup>
```
