docs: note about preview deploy

components/common/CommonPreviewPrompt.vue

@@ -0,0 +1,27 @@
+<script setup lang="ts">
+const build = useBuildInfo()
+</script>
+
+<template>
+  <div
+    m-2 p5 bg-rose:10 relative
+    rounded-lg of-hidden
+    flex="~ col gap-3"
+  >
+    <h2 font-bold text-rose>
+      {{ $t('help.build_preview.title') }}
+    </h2>
+    <p>
+      <i18n-t keypath="help.build_preview.desc1">
+        <NuxtLink :href="`https://github.com/elk-zone/elk/commit/${build.commit}`" target="_blank" text-rose hover:underline>
+          <code>{{ build.commit.slice(0, 7) }}</code>
+        </NuxtLink>
+      </i18n-t>
+    </p>
+    <p>{{ $t('help.build_preview.desc2') }}</p>
+    <p font-bold>
+      {{ $t('help.build_preview.desc3') }}
+    </p>
+    <div i-ri-git-pull-request-line absolute text-10em bottom--10 inset-ie--10 text-rose op10 class="-z-1" />
+  </div>
+</template>