docs(google-maps): Document the behavior of using the clusterClick output in MapMarkerClusterer (#33404)

Added detailed documentation for clusterClick output.

(cherry picked from commit bcb08ec)

Author: jermowery

src/google-maps/map-marker-clusterer/map-marker-clusterer.ts

@@ -82,7 +82,11 @@ export class MapMarkerClusterer implements OnInit, OnChanges, OnDestroy {
   @Output() readonly clusteringend: Observable<void> =
     this._closestMapEventManager.getLazyEmitter<void>('clusteringend');
 
-  /** Emits when a cluster has been clicked. */
+  /**
+   * Emits when a cluster has been clicked.
+   * Listening to this output will replace the default click handler on the cluster,
+   * disabling the default behavior of zooming into the markers in the cluster.
+   */
   @Output()
   readonly clusterClick: EventEmitter<Cluster> = new EventEmitter<Cluster>();