chore: whitespace changes suggested by Prettier

vuejs/docs@42f3656#diff-4d47e7364676bfe0411297303264e00087269482dd4665c4fc9b139dfae30fbc

Author: naokie

src/guide/reactivity.md

@@ -98,7 +98,7 @@ But knowing what code is running is just one part of the puzzle. How does Vue kn
 
 We can't track reassignments of local variables like those in our earlier examples, there's just no mechanism for doing that in JavaScript. What we can track are changes to object properties.
 
-When we return a plain JavaScript object from a component's `data` function, Vue will wrap that object in a [Proxy](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy) with handlers for `get` and `set`. Proxies were introduced in ES6 and allow Vue 3 to avoid some of the reactivity caveats that existed in earlier versions of Vue. 
+When we return a plain JavaScript object from a component's `data` function, Vue will wrap that object in a [Proxy](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy) with handlers for `get` and `set`. Proxies were introduced in ES6 and allow Vue 3 to avoid some of the reactivity caveats that existed in earlier versions of Vue.
 
 <div class="reactivecontent">
   <common-codepen-snippet title="Proxies and Vue's Reactivity Explained Visually" slug="VwmxZXJ" tab="result" theme="light" :height="500" :editable="false" :preview="false" />