docs(ecommerce): update

Author: MatteoGabriele

README.md

@@ -51,6 +51,7 @@ npm install vue-analytics
 * [Track multiple accounts](/docs/track-multiple-accounts.md)
 * [On Analaytics script ready](/docs/when-google-analytics-is-loaded.md)
 * [Custom methods](/docs/custom-methods.md)
+* [Ecommerce](/docs/ecommerce.md)
 * [Debug](/docs/debug.md)
 
 # Issues and features requests

docs/ecommerce.md

@@ -0,0 +1,44 @@
+## Ecommerce
+
+All ecommerce features are built-in in the plugin, so there's no need to require any ecommerce libraries: just enable the ecommerce features from the plugin configuration
+
+```js
+import Vue from 'vue'
+import VueAnalytics from 'vue-analytics'
+
+Vue.use(VueAnalytics, {
+  id: 'UA-XXX-X',
+  ecommerce: {
+    enabled: true
+  }
+})
+```
+
+It is also possible to use the Enhanced Ecommerce library just by change it the configuration like so
+
+```js
+Vue.use(VueAnalytics, {
+  id: 'UA-XXX-X',
+  ecommerce: {
+    enabled: true,
+    enhanced: true
+  }
+})
+```
+
+Finally it's possible to pass addition option during the installation of the library
+
+```js
+Vue.use(VueAnalytics, {
+  id: 'UA-XXX-X',
+  ecommerce: {
+    enabled: true,
+    options: { ... }
+  }
+})
+```
+
+All the available features are documented in Google Analytics dev guide
+
+- [Ecommerce](https://developers.google.com/analytics/devguides/collection/analyticsjs/ecommerce)
+- [Enhanced Ecommerce](https://developers.google.com/analytics/devguides/collection/analyticsjs/enhanced-ecommerce)