Update README.md with @supports documentation (#231)

https://developer.mozilla.org/en-US/docs/Web/CSS/@supports

Author: Leo Taifa Merinen

README.md

@@ -376,7 +376,7 @@ test('it applies styles according to passed props', () => {
 })
 ```
 
-The matcher supports an optional third `options` parameter which makes it possible to search for rules nested within an [At-rule](https://developer.mozilla.org/en/docs/Web/CSS/At-rule) ([media](https://developer.mozilla.org/en-US/docs/Web/CSS/@media)) or to add modifiers to the class selector. This feature is supported in React only, and more options are coming soon.
+The matcher supports an optional third `options` parameter which makes it possible to search for rules nested within an [At-rule](https://developer.mozilla.org/en/docs/Web/CSS/At-rule) (see [media](https://developer.mozilla.org/en-US/docs/Web/CSS/@media) and [supports](https://developer.mozilla.org/en-US/docs/Web/CSS/@supports)) or to add modifiers to the class selector. This feature is supported in React only, and more options are coming soon.
 
 ```js
 const Button = styled.button`