message: docs: note about transition and initial navigation
diff: @@ -37,6 +37,13 @@ Since the library is still unstable **and because we want feedback** on bugs and
  ],
  }
  ```
  +- If you use a `transition`, you need to wait for the router to be _ready_ before mounting the app:
  + ```js
  + app.use(router)
  + // Note: on Server Side, you need to manually push the initial location
  + router.isReady().then(() => app.mount('#app'))
  + ```
  + Otherwise there will be an initial transition as if you provided the `appear` prop to `transition`
  #### Improvements
  