fix(docs): move Vite config 'plugins' property (#506)

---------

Co-authored-by: gioboa <giorgiob.boa@gmail.com>

docs/copy-library-files.md

@@ -80,13 +80,11 @@ import path from 'path';
 import { partytownVite } from '@builder.io/partytown/utils';
 
 export default ({ command }) => ({
-  build: {
-    plugins: [
-      partytownVite({
-        dest: path.join(__dirname, 'dist', '~partytown'),
-      }),
-    ],
-  },
+  plugins: [
+    partytownVite({
+      dest: path.join(__dirname, 'dist', '~partytown'),
+    }),
+  ],
 });
 ```
 
@@ -106,14 +104,14 @@ module.exports = {
       patterns: [
         {
           from: partytown.libDirPath(),
-          to: path.join(__dirname, "public", "~partytown"),
+          to: path.join(__dirname, 'public', '~partytown'),
         },
       ],
     }),
   ],
 };
-
 ```
+
 ## Laravel Mix
 
 Below is an example of using [Mix's copy()](https://laravel-mix.com/docs/6.0/copying-files/) to copy the source `lib` directory found in the [@builder.io/partytown](https://www.npmjs.com/package/@builder.io/partytown) package, to the `public/~partytown/` directory: