docs(upgrade): move examples etc into @usageNotes (#26039)

PR Close #26039

packages/upgrade/src/common/downgrade_component.ts

@@ -29,6 +29,7 @@ interface Thenable<T> {
  * This helper function returns a factory function to be used for registering
  * an AngularJS wrapper directive for "downgrading" an Angular component.
  *
+ * @usageNotes
  * ### Examples
  *
  * Let's assume that you have an Angular component called `ng2Heroes` that needs

packages/upgrade/src/common/downgrade_injectable.ts

@@ -20,6 +20,7 @@ import {INJECTOR_KEY} from './constants';
  * This helper function returns a factory function that provides access to the Angular
  * service identified by the `token` parameter.
  *
+ * @usageNotes
  * ### Examples
  *
  * First ensure that the service to be downgraded is provided in an `NgModule`