feat(docs): Add vitepress for docs & docs workspace

docs/.vitepress/theme/index.ts

@@ -0,0 +1,10 @@
+import { Theme } from 'vitepress';
+import DefaultTheme from 'vitepress/theme'
+import Demo from '../components/Demo.vue'
+
+export default {
+  ...DefaultTheme,
+  enhanceApp({ app }) {
+    app.component('Demo', Demo)
+  }
+} as Theme