Update composition-api-faq.md (#2338)

The links for the examples (immutable data, state machines and RxJS) should be consistent and point to the guide's definition

Author: leoelz

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

@@ -55,7 +55,7 @@ If you are interested in learning how to use Vue with Composition API, you can s
 
 The primary advantage of Composition API is that it enables clean, efficient logic reuse in the form of [Composable functions](/guide/reusability/composables). It solves [all the drawbacks of mixins](/guide/reusability/composables#vs-mixins), the primary logic reuse mechanism for Options API.
 
-Composition API's logic reuse capability has given rise to impressive community projects such as [VueUse](https://vueuse.org/), an ever-growing collection of composable utilities. It also serves as a clean mechanism for easily integrating stateful third-party services or libraries into Vue's reactivity system, for example [immutable data](/guide/extras/reactivity-in-depth#immutable-data), [state machines](/guide/extras/reactivity-in-depth#state-machines), and [RxJS](https://vueuse.org/rxjs/readme.html#vueuse-rxjs).
+Composition API's logic reuse capability has given rise to impressive community projects such as [VueUse](https://vueuse.org/), an ever-growing collection of composable utilities. It also serves as a clean mechanism for easily integrating stateful third-party services or libraries into Vue's reactivity system, for example [immutable data](/guide/extras/reactivity-in-depth#immutable-data), [state machines](/guide/extras/reactivity-in-depth#state-machines), and [RxJS](/guide/extras/reactivity-in-depth#rxjs).
 
 ### More Flexible Code Organization {#more-flexible-code-organization}