docs(ComponentExample): automatically read code (#789)

docs/content/3.forms/2.textarea.md

@@ -10,21 +10,7 @@ links:
 
 Use a `v-model` to make the Textarea reactive.
 
-::component-example
-#default
-:textarea-example
-
-#code
-```vue
-<script setup>
-const value = ref('')
-</script>
-
-<template>
-  <UTextarea v-model="value" />
-</template>
-```
-::
+:component-example{component="textarea-example"}
 
 ### Style