chore: include plugins internal usage as warning

guide/inject-manifest.md

@@ -81,11 +81,13 @@ injectManifest: {
 
 ### Custom Rollup and Vite Plugins <Badge type="tip" text="from v0.18.0+" />
 
-From `v0.18.0`, you can add custom Rollup and/or Vite plugins to the service worker build, using `rollup` and `vite` in `buildPlugins` options.
+From `v0.18.0`, you can add custom Rollup and/or Vite plugins to the service worker build, using `rollup` and `vite` options in the new `buildPlugins` option.
 
+::: warning
 The old `plugins` option has been deprecated, use `buildPlugins.rollup` instead: 
 - if `buildPlugins.rollup` is configured then `plugins` will be ignored
 - if `buildPlugins.rollup` is not configured then `plugins` will be used
+:::
 
 You can check the [vue-router example](https://github.com/vite-pwa/vite-plugin-pwa/tree/main/examples/vue-router) using a custom Vite plugin with a simple virtual module consumed by both custom service workers.