spruce up the readme

Author: developit

README.md

@@ -1,13 +1,22 @@
-# rollup-plugin-postprocess
+# rollup-plugin-postprocess [![npm](https://img.shields.io/npm/v/rollup-plugin-postprocess.svg?style=flat)](https://www.npmjs.org/package/rollup-plugin-postprocess) [![travis](https://travis-ci.org/developit/rollup-plugin-postprocess.svg?branch=master)](https://travis-ci.org/developit/rollup-plugin-postprocess)
 
 Apply regex find-and-replace postprocessing to your Rollup bundle.
 
+
 ## Installation
 
 `npm i -D rollup-plugin-postprocess`
 
+
 ## Usage
 
+Works just like a [JavaScript String replace](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace), including the funtion callback option.
+
+`postprocess()` expects an Array of `[(RexExp) find, (String|Function) replace]` pairs. Alternatively, if a function is provided, it will be invoked for each bundle and can return said pairs.
+
+
+## Example
+
 ```js
 import postprocess from 'rollup-plugin-postprocess';