docs: Add more pending tasks documentation in zoneless readme (angular#59689)

This commit expands on the pending tasks documentation in the zoneless readme

PR Close angular#59689

Author: atscott

adev/src/content/guide/zoneless.md

@@ -86,14 +86,39 @@ are used in applications that still rely on ZoneJS.
 
 If you are using SSR with Angular, you may know that it relies on ZoneJS to help determine when the application
 is "stable" and can be serialized. If there are asynchronous tasks that should prevent serialization, an application
-not using ZoneJS will need to make Angular aware of these with the `PendingTasks` service. Serialization
+not using ZoneJS must make Angular aware of these with the [PendingTasks](/api/core/PendingTasks) service. Serialization
 will wait for the first moment that all pending tasks have been removed.
 
+
+The two most straightforward uses of pending tasks are the `run` method:
+
+```typescript
+const taskService = inject(PendingTasks);
+taskService.run(async () => {
+  const someResult = await doSomeWorkThatNeedsToBeRendered();
+  this.someState.set(someResult);
+});
+```
+
+For more complicated use-cases, you can manuall add and remove a pending tasks:
+
 ```typescript
 const taskService = inject(PendingTasks);
 const taskCleanup = taskService.add();
-await doSomeWorkThatNeedsToBeRendered();
-taskCleanup();
+try {
+  await doSomeWorkThatNeedsToBeRendered();
+} catch {
+  // handle error
+} finally {
+  taskCleanup();
+}
+```
+
+In addition, the [pendingUntilEvent](/api/core/rxjs-interop/pendingUntilEvent#) helper in `rxjs-interop` ensures
+the application remains unstable until the observable emits, complets, errors, or is unsubscribed.
+
+```typescript
+readonly myObservableState = someObservable.pipe(pendingUntilEvent());
 ```
 
 The framework uses this service internally as well to prevent serialization until asynchronous tasks are complete. These include, but are not limited to,