docs: add playground and demo link

README.md

@@ -14,9 +14,9 @@ Nuxt Module for Apache ECharts™
 > Nuxt ECharts is currently in active development and based on [experimental `<NuxtIsland>`](https://nuxt.com/docs/api/components/nuxt-island). If you found any issue, design flaw, or have ideas to improve it, please open an [issue](https://github.com/kingyue737/nuxt-echarts/issues) or a [Discussion](https://github.com/kingyue737/nuxt-echarts/discussions).
 
 - [✨ &nbsp;Release Notes](/CHANGELOG.md)
-- 🏀 &nbsp;Online playground (WIP)
+- [🎞️ &nbsp;Online Demo](https://nuxt-echarts.nuxt.dev/)
+- [🏀 &nbsp;Online playground](https://stackblitz.com/github/kingyue737/nuxt-echarts?file=playground%2Fapp.vue)
 - 📖 &nbsp;Documentation (WIP)
-  <!-- - [🏀 Online playground](https://stackblitz.com/github/kingyue737/nuxt-echarts?file=playground%2Fapp.vue) -->
   <!-- - [📖 &nbsp;Documentation](https://example.com) -->
 
 ## Features