Updated docs with urlArgs functionality.

Author: Boye

README.md

@@ -149,6 +149,16 @@ $script.get('http://example.com/base.js', function () {
 })
 ```
 
+### $script.urlArgs()
+As of 2.5.5 it's possible to concat URL arguments (i.e. a query string) to the script path.
+This is especially useful when you're in need of a cachebuster and works as follows:
+
+```js
+$script.urlArgs('key=value&foo=bar');
+``` 
+
+Please note that Squid, a popular proxy, doesn’t cache resources with a querystring. This hurts performance when multiple users behind a proxy cache request the same file – rather than using the cached version everybody would have to send a request to the origin server. So ideally, [as Steve Souders points out](http://www.stevesouders.com/blog/2008/08/23/revving-filenames-dont-use-querystring/), you should rev the filename itself.
+
 ### Developers
 
 Building a $script environment works like this: