docs: Minor template improvement

Author: medikoo

README.md

@@ -16,7 +16,9 @@ When used in ECMAScript 6 environment, native implementation (if valid) takes pr
 
 ### Installation
 
-    $ npm install es5-ext
+```bash
+npm install es5-ext
+```
 
 To port it to Browser or any other (non CJS) environment, use your favorite CJS bundler. No favorite yet? Try: [Browserify](http://browserify.org/), [Webmake](https://github.com/medikoo/modules-webmake) or [Webpack](http://webpack.github.io/)