Add doc on sprite.

README.md

@@ -59,6 +59,54 @@ const control = new LevelControl(indoorEqual);
 map.addControl(control);
 ```
 
+## Loading the default sprite
+
+The default style make uses of a sprite that has to be loaded manually and require an absolute path. The sprite is already builded and available in the `sprite` directory.
+
+To load the sprite, set the `spriteBaseUrl` property option on the constructor with the absolute path to the sprite and its name `/directory-to-change/indoorequal`.
+
+**Usage with [Parcel](https://parceljs.org/)**
+
+Install the
+[parcel-plugin-static-files-copy](https://github.com/elwin013/parcel-plugin-static-files-copy)
+package and add to your `package.json`:
+
+    "staticFiles": {
+      "staticPath": "node_modules/openlayers-indoorequal/sprite"
+    },
+
+Then load the sprite:
+
+```javascript
+const indoorequal = new IndoorEqual(map, { apiKey: 'myKey', spriteBaseUrl: '/indoorequal' });
+```
+
+**Usage with [webpack](https://webpack.js.org/)**
+
+Install the
+[copy-webpack-plugin](https://github.com/webpack-contrib/copy-webpack-plugin)
+package and add to your webpack config:
+
+```javascript
+const CopyPlugin = require('copy-webpack-plugin');
+
+module.exports = {
+  plugins: [
+    new CopyPlugin({
+      patterns: [
+        { from: 'node_modules/openlayers-indoorequal/sprite' },
+      ],
+    }),
+  ],
+};
+```
+
+Then load the sprite:
+
+```javascript
+const indoorequal = new IndoorEqual(map, { apiKey: 'myKey', spriteBaseUrl: '/indoorequal' });
+```
+
 ## API
 
 <!-- Generated by documentation.js. Update this documentation by updating the source code. -->