syntax highlighting on codeblocks in README

Author: jscottsmith

README.md

@@ -24,21 +24,21 @@ npm i react-scroll-parallax
 
 Import `ParallaxController` on the client side and call `ParallaxController.init()` to create the global `ParallaxController` which will handle updating all parallax elements on scroll.
 
-```
+```javascript
 import { ParallaxController } from 'react-scroll-parallax';
 
 ParallaxController.init();
 ```
 
 Import the `Parallax` component...
 
-```
+```javascript
 import { Parallax } from 'react-scroll-parallax';
 ```
 
 ... then use it like so:
 
-```
+```jsx
 <Parallax
     className="custom-class"
     offsetYMax={20}