docs(storybook): upgrade to storybook 6 (#111)

Author: jaebradley

.storybook/main.js

@@ -1,10 +1,9 @@
 module.exports = {
   stories: ['../src/**/*.stories.jsx'],
   addons: [
-    '@storybook/addon-options/register',
-    '@storybook/addon-actions/register',
-    '@storybook/addon-a11y/register',
-    '@storybook/addon-notes/register',
+    {
+      name: '@storybook/addon-essentials',
+    },
   ],
 };