chore: backport retro compatible commits for the Docusaurus v2.1 release (#8033)

Co-authored-by: sebastienlorber <lorber.sebastien@gmail.com>
Co-authored-by: Joshua Chen <sidachen2003@gmail.com>
Co-authored-by: Sébastien Lorber <slorber@users.noreply.github.com>
Co-authored-by: whiteand <andrewbeletskiy@gmail.com>
Co-authored-by: yzhe819 <68207314+yzhe819@users.noreply.github.com>
Co-authored-by: Ngô Quốc Đạt <56961917+datlechin@users.noreply.github.com>
Co-authored-by: Kevin Østerkilde <kevin@oesterkilde.dk>
Co-authored-by: Bagdasar Ovsepyan <66012777+b-ovsepian@users.noreply.github.com>
Co-authored-by: Yoni Chechik <chechik.yoni@gmail.com>
Co-authored-by: adventure-yunfei <adventure.yunfei@gmail.com>
Co-authored-by: Morgane Dubus <30866152+mdubus@users.noreply.github.com>

packages/create-docusaurus/templates/shared/docs/tutorial-basics/congratulations.md

@@ -14,7 +14,9 @@ Anything **unclear** or **buggy** in this tutorial? [Please report it!](https://
 
 ## What's next?
 
-- Read the [official documentation](https://docusaurus.io/).
+- Read the [official documentation](https://docusaurus.io/)
+- Modify your site configuration with [`docusaurus.config.js`](https://docusaurus.io/docs/api/docusaurus-config)
+- Add navbar and footer items with [`themeConfig`](https://docusaurus.io/docs/api/themes/configuration)
 - Add a custom [Design and Layout](https://docusaurus.io/docs/styling-layout)
 - Add a [search bar](https://docusaurus.io/docs/search)
 - Find inspirations in the [Docusaurus showcase](https://docusaurus.io/showcase)

packages/create-docusaurus/templates/shared/docs/tutorial-basics/create-a-document.md

@@ -44,11 +44,13 @@ It is also possible to create your sidebar explicitly in `sidebars.js`:
 ```js title="sidebars.js"
 module.exports = {
   tutorialSidebar: [
+    'intro',
+    // highlight-next-line
+    'hello',
     {
       type: 'category',
       label: 'Tutorial',
-      // highlight-next-line
-      items: ['hello'],
+      items: ['tutorial-basics/create-a-document'],
     },
   ],
 };