fix: add missing anchors on suspense (#2795)

src/guide/built-ins/suspense.md

@@ -133,7 +133,7 @@ The following example shows how to nest these components so that they all behave
 
 Vue Router has built-in support for [lazily loading components](https://router.vuejs.org/guide/advanced/lazy-loading.html) using dynamic imports. These are distinct from async components and currently they will not trigger `<Suspense>`. However, they can still have async components as descendants and those can trigger `<Suspense>` in the usual way.
 
-## Nested Suspense
+## Nested Suspense {#nested-suspense}
 
 When we have multiple async components (common for nested or layout-based routes) like this: