docs: add donate button to readme

README.md

@@ -1,6 +1,6 @@
 ![Showdown][sd-logo]
 
-[![Build Status](https://travis-ci.org/showdownjs/showdown.svg?branch=master)](https://travis-ci.org/showdownjs/showdown) [![npm version](https://badge.fury.io/js/showdown.svg)](http://badge.fury.io/js/showdown) [![Bower version](https://badge.fury.io/bo/showdown.svg)](http://badge.fury.io/bo/showdown) [![Join the chat at https://gitter.im/showdownjs/showdown](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/showdownjs/showdown?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) [![Greenkeeper badge](https://badges.greenkeeper.io/showdownjs/showdown.svg)](https://greenkeeper.io/)
+[![Build Status](https://travis-ci.org/showdownjs/showdown.svg?branch=master)](https://travis-ci.org/showdownjs/showdown) [![npm version](https://badge.fury.io/js/showdown.svg)](http://badge.fury.io/js/showdown) [![Bower version](https://badge.fury.io/bo/showdown.svg)](http://badge.fury.io/bo/showdown) [![Join the chat at https://gitter.im/showdownjs/showdown](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/showdownjs/showdown?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) [![Greenkeeper badge](https://badges.greenkeeper.io/showdownjs/showdown.svg)](https://greenkeeper.io/) [![gitcheese.com](https://api.gitcheese.com/v1/projects/7a79ccaa-2d76-447e-9637-8c6ec37fd9ff/badges)](https://www.gitcheese.com/app/#/projects/7a79ccaa-2d76-447e-9637-8c6ec37fd9ff/pledges/create)
 
 ------
 
@@ -20,6 +20,9 @@ Check a live Demo here http://showdownjs.github.io/demo/
  - [docular](https://github.com/Vertafore/docular)
  - [and some others...](https://www.npmjs.com/browse/depended/showdown)
 
+## Donate [![gitcheese.com](https://api.gitcheese.com/v1/projects/7a79ccaa-2d76-447e-9637-8c6ec37fd9ff/badges)](https://www.gitcheese.com/app/#/projects/7a79ccaa-2d76-447e-9637-8c6ec37fd9ff/pledges/create)
+
+We're currently looking to improve showdown with automated tests in all browsers and a proper domain and webpage. If you like our work, please donate!! Your contribution will be greatly appreciated.
 
 ## Installation