Bug 1890586 - Fix broken Storybook link in Source Docs. r=reusable-components-reviewers,mstriemer

This also makes the Storybook overview doc the first in the list, so
that https://firefoxux.github.io/firefox-desktop-components/ will show
the Storybook overview doc on the redirect.

Differential Revision: https://phabricator.services.mozilla.com/D207074

browser/components/storybook/.storybook/main.js

@@ -13,6 +13,10 @@ const projectRoot = path.resolve(__dirname, "../../../../");
 module.exports = {
   // The ordering for this stories array affects the order that they are displayed in Storybook
   stories: [
+    // Show the Storybook document first in the list
+    // so that navigating to firefoxux.github.io/firefox-desktop-components/
+    // lands on the Storybook.stories.md file
+    "../**/README.storybook.stories.md",
     // Docs section
     "../**/README.*.stories.md",
     // UI Widgets section

browser/components/storybook/docs/README.storybook.stories.md

@@ -4,7 +4,7 @@
 playground for UI components. We use Storybook to document our design system,
 reusable components, and any specific components you might want to test with
 dummy data. [Take a look at our Storybook
-instance!](https://firefoxux.github.io/firefox-desktop-components/?path=/story/docs-reusable-widgets--page)
+instance!](https://firefoxux.github.io/firefox-desktop-components/)
 
 ## Background