feat: docusaurus.new + improved StackBlitz playground (#5235)

* Upgrade playground shortcut domain to docusaurus.new

* update generateExamples

* update generateExamples + re-generate with stackblitz config

* test

* test

* test

* test

* test

* update examples

* upgrade lockfile

* fix yarnlock

* fix yarnlock

.stackblitzrc

@@ -0,0 +1,4 @@
+{
+  "installDependencies": true,
+  "startCommand": "npm start"
+}

package.json

@@ -15,8 +15,8 @@
     "dev": "docusaurus start"
   },
   "dependencies": {
-    "@docusaurus/core": "2.0.0-beta.2",
+    "@docusaurus/core": "2.0.0-beta.3",
-    "@docusaurus/preset-classic": "2.0.0-beta.2",
+    "@docusaurus/preset-classic": "2.0.0-beta.3",
     "@mdx-js/react": "^1.6.21",
     "@svgr/webpack": "^5.5.0",
     "clsx": "^1.1.1",