The `<Summary />` component defines a visible heading for the `<Details />` element. The heading can be clicked to view/hide the details. 
This component has no props.

`<Summary />` component example:

```js
import { Details, Summary, P } from '$PACKAGE_NAME';

<Details>
  <Summary>Copyright 2016-2018.</Summary>
  <P> - by YeuTech All Rights Reserved.</P>
  <P>All content and graphics on this web site are the property of the company YeuTech.</P>
</Details>
```
