Add `props` example to docs/vue.md (#2959)

website/src/docs/vue.md

@@ -35,7 +35,7 @@ Instead of adding a UI plugin to an Uppy instance with `.use()`, the Uppy instan
 ```html
 <template>
   <div id="app">
-    <dashboard :uppy="uppy" :plugins="['Webcam']"/>
+    <dashboard :uppy="uppy" :plugins="['Webcam']" :props="{theme: 'light'}" />
   </div>
 </template>