Fix broken link (#2218)

Author: xfq

src/guide/extras/composition-api-faq.md

@@ -10,7 +10,7 @@ This FAQ assumes prior experience with Vue - in particular, experience with Vue
 
 ## What is Composition API? {#what-is-composition-api}
 
-<VueSchoolLink href="[https://vueschool.io/lessons/computed-properties-in-vue-3](https://vueschool.io/lessons/introduction-to-the-vue-js-3-composition-api)" title="Free Composition API Lesson"/>
+<VueSchoolLink href="https://vueschool.io/lessons/introduction-to-the-vue-js-3-composition-api" title="Free Composition API Lesson"/>
 
 Composition API is a set of APIs that allows us to author Vue components using imported functions instead of declaring options. It is an umbrella term that covers the following APIs: