docs(icons): dynamic theme section

docs/app/components/content/IconsTheme.vue

@@ -0,0 +1,19 @@
+<script setup lang="ts">
+import json5 from 'json5'
+
+const appConfig = useAppConfig()
+
+const { data: ast } = await useAsyncData<any>(`icons-theme`, () => parseMarkdown(`
+\`\`\`yml
+${json5.stringify(appConfig.ui.icons, null, 2).replace(/,([ |\t\n]+[}|\])])/g, '$1')}
+\`\`\`\
+
+::callout{icon="i-heroicons-light-bulb"}
+You can customize this component in your \`app.config.ts\` under \`ui.icons\` key.
+::
+`))
+</script>
+
+<template>
+  <MDCRenderer v-if="ast" :body="ast.body" :data="ast.data" />
+</template>