Improve doc about GA

.storybook/main.js

@@ -1,11 +1,20 @@
 module.exports = {
-  'stories': [
+  stories: [
     '../src/**/*.stories.mdx',
     '../src/**/*.stories.@(js|jsx|ts|tsx)',
   ],
-  'addons': [
+  addons: [
     '@storybook/addon-links',
     '@storybook/addon-essentials',
+
+    /**
+     * We use Google Analytics for tracking analytics usage.
+     *
+     * It's much easier to setup than Amplitude, because there is an official dedicated plugin for this.
+     * See ".storybook/manager.js" for Google Analytics configuration.
+     *
+     * @see https://github.com/storybookjs/storybook/tree/master/addons/google-analytics
+     */
     '@storybook/addon-google-analytics',
   ],
 };

.storybook/preview.js

@@ -29,11 +29,7 @@ import dataset from './mock/sb-dataset';
  * - We don't want to track analytics using Amplitude.
  * - All analytics is disabled when running a component through Storybook preview.
  *
- * About Google analytics:
- * - We use Google Analytics for tracking analytics usage.
- * - It's much easier to setup than Amplitude, because there is an official dedicated plugin for this.
- * - See ".storybook/manager.js" for GA configuration.
- * - See https://github.com/storybookjs/storybook/tree/master/addons/google-analytics
+ * About Google analytics, see ".storybook/main.js" documentation.
  */
 const customer = find(dataset, { __typename: 'Customer' });
 const customerTheme = initCustomerTheme(customer);