Adds instructions to generate the icon font in the README

README.md

@@ -2,7 +2,6 @@
 
 > Share frontend assets between different CartoDB repositories
 
-
 ### Installation
 As easy as:
 - ```npm install```
@@ -29,3 +28,32 @@ If you have these previous steps done:
 Just run this command:
 
 - ```grunt publish```
+
+How to make changes in the CartoDB icon font
+--------------------------------------------
+
+If you want to edit, add or remove any icon in our CartoDB font, you should follow these steps:
+
+- Check you have [Sketch](http://bohemiancoding.com/sketch/) last version.
+- Open [font.sketch](http://github.com/CartoDB/CartoAssets/blob/master/icon_font/font.sketch) file and make your changes.
+
+### Rules for the icons:
+- Size should have at max 500px of width/height.
+- Place the icon accordingly with the grid.
+- Icons should be completely black.
+- Group the icon if it has several parts.
+- Make icons exportable to SVG.
+- Name your icon (layer/group) according to the pattern `icon-font_xx_Name`, where xx is a unique integer (increase it for each new icon).
+
+### When you're done with changes
+
+- Select all the icons, and export them to `app/assets/fonts/icon_font/svgs` folder (option should be visible in the bottom corner in your Sketch app):
+  - ![screen shot 2015-01-16 at 11 40 36](https://cloud.githubusercontent.com/assets/978461/5774986/93dc90e8-9d74-11e4-8064-a478e55d392b.png)
+  - Take into account that ```svgs``` folder is ignored.
+- Open your terminal app and go to the CartoDB root folder.
+- Install your node dependencies: `npm install`
+- Now we will generate the new icon fonts + stylesheet. Just run: `./node_modules/.bin/gulp`
+- Check that your `icon-font.css.scss` and the `cartoIcon` fonts have been edited: 
+  - ![screen shot 2015-01-16 at 11 02 53](https://cloud.githubusercontent.com/assets/978461/5775004/acf10faa-9d74-11e4-893c-790da626d894.png)
+
+All done!