chore: add demo

Close #213

Author: posva

README.md

@@ -10,6 +10,8 @@
   <img src="https://user-images.githubusercontent.com/664177/176623167-0153f9fb-79cd-49a7-8575-429ce323dd11.gif" >
 </p>
 
+- [StackBlitz Demo](https://stackblitz.com/github/posva/uvr-demo)
+
 This build-time plugin simplifies your routing setup **and** makes it safer and easier to use thanks to TypeScript. Requires Vue Router at least 4.1.0.
 
 ⚠️ This package is still experimental. If you found any issue, design flaw, or have ideas to improve it, please, open an [issue](https://github.com/posva/unplugin-vue-router/issues/new/choose) or a [Discussion](https://github.com/posva/unplugin-vue-router/discussions).