(docs) Add Donation section

README.md

@@ -7,6 +7,7 @@
 [![npm](https://img.shields.io/npm/dm/baguettebox.js.svg)](https://www.npmjs.com/package/baguettebox.js)
 [![Build Status](https://travis-ci.org/feimosi/baguetteBox.js.svg?branch=master)](https://travis-ci.org/feimosi/baguetteBox.js)
 
+[![Donate](https://img.shields.io/badge/Donate-PayPal-green.svg)](https://paypal.me/feimosi)
 [![Twitter](https://img.shields.io/twitter/url/http/shields.io.svg?style=social)](https://twitter.com/intent/tweet?text=Check%20out%20baguetteBox.js%20-%20simple%20and%20easy%20to%20use%20lightbox%20script%20written%20in%20pure%20JavaScript%0Ahttps%3A%2F%2Fgithub.com%2Ffeimosi%2FbaguetteBox.js)
 [![Twitter Follow](https://img.shields.io/twitter/follow/feimosi.svg?style=social&label=Follow%20the%20author)](https://twitter.com/feimosi)
 
@@ -27,6 +28,7 @@ Simple and easy to use lightbox script written in pure JavaScript.
   * [Responsive images](#responsive-images)
   * [Compatibility](#compatibility)
   * [Contributing](#contributing)
+  * [Donation](#donation)
   * [Credits](#credits)
   * [License](#license)
 
@@ -248,6 +250,12 @@ Mobile:
 
 Feel free to report any issues! If you wish to contribute by fixing a bug or implementing a new feature, please first read the [CONTRIBUTING](./CONTRIBUTING.md) guide.
 
+## Donation
+
+If you find this project useful and want to say thanks, you can buy me a cup of coffee :)
+
+[![](https://www.paypalobjects.com/en_US/i/btn/btn_donateCC_LG.gif)](https://paypal.me/feimosi)
+
 ## Credits
 
 Creation of `baguetteBox.js` was inspired by a great jQuery plugin [touchTouch](https://github.com/martinaglv/touchTouch).