docs: fix code block highlights (vuejs#1387)

Co-authored-by: liuyao <[email protected]>

packages/docs/getting-started.md

@@ -16,7 +16,7 @@ If you are using the Vue CLI, you can instead give this [**unofficial plugin**](
 
 Create a pinia instance (the root store) and pass it to the app as a plugin:
 
-```js{2,5-6,8}
+```js {2,5-6,8}
 import { createApp } from 'vue'
 import { createPinia } from 'pinia'
 import App from './App.vue'
@@ -30,7 +30,7 @@ app.mount('#app')
 
 If you are using Vue 2, you also need to install a plugin and inject the created `pinia` at the root of the app:
 
-```js{1,3-4,12}
+```js {1,3-4,12}
 import { createPinia, PiniaVuePlugin } from 'pinia'
 
 Vue.use(PiniaVuePlugin)

packages/docs/introduction.md

@@ -77,7 +77,7 @@ export const useCounterStore = defineStore('counter', () => {
 
 If you are still not into `setup()` and Composition API, don't worry, Pinia also support a similar set of [_map helpers_ like Vuex](https://vuex.vuejs.org/guide/state.html#the-mapstate-helper). You define stores the same way but then use `mapStores()`, `mapState()`, or `mapActions()`:
 
-```js{22,24,28}
+```js {22,24,28}
 const useCounterStore = defineStore('counter', {
   state: () => ({ count: 0 }),
   getters: {