build(storybook): set up analytics addon

so that we get an idea how many people are looking at our storybook :-)

Author: urish

.storybook/addons.js

@@ -1,3 +1,8 @@
 module.exports = {
-  addons: ['@storybook/addon-docs'],
+  addons: [
+    '@storybook/addon-actions/register',
+    '@storybook/addon-docs',
+    '@storybook/addon-google-analytics/register',
+    '@storybook/addon-knobs/register',
+  ],
 };

.storybook/main.js

@@ -0,0 +1 @@
+window.STORYBOOK_GA_ID = 'UA-150413053-2';

.storybook/manager.js

@@ -14,6 +14,7 @@
     "@babel/core": "^7.7.5",
     "@storybook/addon-actions": "^5.3.17",
     "@storybook/addon-docs": "^5.3.17",
+    "@storybook/addon-google-analytics": "^5.3.17",
     "@storybook/addon-knobs": "^5.3.17",
     "@storybook/web-components": "^5.3.17",
     "@typescript-eslint/eslint-plugin": "^2.10.0",