Add a README file for storybook directory (#18245)

* Add a README file for storybook directory

* Fix typo

packages/components/storybook/README.md

@@ -0,0 +1,11 @@
+
+# Storybook 
+
+Storybook is an open-source tool that provides a sandbox to develop and visualize components in isolation. See the [Storybookjs site](https://storybook.js.org/) for more information about the tool. 
+
+The Gutenberg project uses Storybook to view and work with the `@wordpress/components` package.
+
+View online at: https://wordpress.github.io/gutenberg/design-system/components
+
+Run locally in your development environment running: `npm run design-system:dev` from the top-level Gutenberg directory.
+