Add documentation for useSuspenseFragment (#12356)

Co-authored-by: Maria Elisabeth Schreiber <maria.schreiber@apollographql.com>

docs/source/data/fragments.mdx

@@ -561,7 +561,7 @@ function Item(props: { item: { __typename: 'Item', id: number }}) {
   const { complete, data } = useFragment({
     fragment: ItemFragment,
     fragmentName: "ItemFragment",
-    from: item
+    from: props.item
   });
 
   return <li>{complete ? data.text : "incomplete"}</li>;
@@ -573,7 +573,7 @@ function Item(props) {
   const { complete, data } = useFragment({
     fragment: ITEM_FRAGMENT,
     fragmentName: "ItemFragment",
-    from: item
+    from: props.item
   });
 
   return <li>{complete ? data.text : "incomplete"}</li>;
@@ -589,6 +589,71 @@ function Item(props) {
 
 See the [API reference](../api/react/hooks#usefragment) for more details on the supported options.
 
+<MinVersion version="3.13.0">
+## `useSuspenseFragment`
+</MinVersion>
+
+For those that have integrated with React [Suspense](https://react.dev/reference/react/Suspense), `useSuspenseFragment` is available as a drop-in replacement for `useFragment`. `useSuspenseFragment` works identically to `useFragment` but will suspend while `data` is incomplete.
+
+Let's update the example from the previous section to use `useSuspenseFragment`. First, we'll update our `Item` component and replace `useFragment` with `useSuspenseFragment`. Since we are using Suspense, we no longer have to check for a `complete` property to determine if the result is complete because the component will suspend otherwise.
+
+```tsx
+import { useSuspenseFragment } from "@apollo/client";
+
+function Item(props) {
+  const { data } = useSuspenseFragment({
+    fragment: ITEM_FRAGMENT,
+    fragmentName: "ItemFragment",
+    from: props.item
+  });
+
+  return <li>{data.text}</li>;
+}
+```
+
+Next, we'll will wrap our `Item` components in a `Suspense` boundary to show a loading indicator if the data from `ItemFragment` is not complete. Since we're using Suspense, we'll replace `useQuery` with `useSuspenseQuery` as well:
+
+```tsx
+function List() {
+  const { data } = useSuspenseQuery(listQuery);
+
+  return (
+    <ol>
+      {data.list.map(item => (
+        <Suspense fallback={<Spinner />}>
+          <Item key={item.id} item={item}/>
+        </Suspense>
+      ))}
+    </ol>
+  );
+}
+```
+
+And that's it! Suspense made our `Item` component a bit more succinct since we no longer need to check the `complete` property to determine if we can safely use `data`.
+
+<Note>
+In most cases, `useSuspenseFragment` will not suspend when rendered as a child of a query component. In this example `useSuspenseQuery` loads the full query data before each `Item` is rendered so the `data` inside each fragment is already complete. The `Suspense` boundary in this example ensures that a loading spinner is shown if field data is removed for any given item in the list in the cache, such as when a manual cache update is performed.
+</Note>
+
+### Using `useSuspenseFragment` with `@defer`
+
+`useSuspenseFragment` is helpful when combined with the [`@defer` directive](./directives#defer) to show a loading state while the fragment data is streamed to the query. Let's update our `GetItemList` query to defer loading the `ItemFragment`'s fields.
+
+```graphql
+query GetItemList {
+  list {
+    id
+    ...ItemFragment @defer
+  }
+}
+```
+
+Our list will now render as soon as our list returns but before the data for `ItemFragment` is loaded.
+
+<Caution>
+You **must** ensure that any key fields used to identify the object passed to the `from` option are not deferred. If they are, you risk suspending the `useSuspenseFragment` hook forever. If you need to defer loading key fields, conditionally render the component until the object passed to the `from` option is identifiable by the cache.
+</Caution>
+
 <MinVersion version="3.12.0">
 ## Data masking
 </MinVersion>