Update readme

README.md

 I won't have time to work on this project in the forseeable future.
 PR's are still welcome, so feel free to implement new awesome features!
 
+updating icons
+==============
+
+This project includes a copy of icons from the [game-icons](http://game-icons.net) project,
+which regularly publishes new icons.
+To download these new icons:
+
+- Install Imagemagick
+- Run the following commands from the root of the project:
+  - `npm install`
+  - `node ./resources/tools/update-icons.js`
+
+
 license
 =======
 
 This generator is provided under the terms of the MIT License
 
-Icons are made by various artists, available at http://game-icons.net.
+Icons are made by various artists, available at [http://game-icons.net](http://game-icons.net).
 They are provided under the terms of the Creative Commons 3.0 BY license.