Update migration-build.md

Author: gionkunz

src/migration-build.md

@@ -135,9 +135,10 @@ The following workflow walks through the steps of migrating an actual Vue 2 app
    // vite.config.js
    export default {
      resolve: {
-       alias: {
-         '^vue$': '@vue/compat'
-       }
+       alias: [{
+        find: /^vue$/, replacement: '@vue/compat'
+       }]
+      }
      },
      plugins: [
        vue({