docs: note that plugins factory requires defineConfig from vite-plus

Author: fengmk2

docs/config/troubleshooting.md

@@ -29,6 +29,10 @@ export default defineConfig({
 });
 ```
 
+::: warning
+The plugins factory requires `defineConfig` from `vite-plus`, not from `vite`. Vite's native `defineConfig` does not support factory functions for the `plugins` field.
+:::
+
 ::: info
 The plugins factory works by checking the `VP_COMMAND` environment variable, which is automatically set by `vp` for every command.
 :::