docs(angular): update overview version support to Angular 18-21 for v9

Author: ShaneK

docs/angular/overview.md

@@ -18,7 +18,7 @@ import DocsCards from '@components/global/DocsCards';
 
 ## Angular Version Support
 
-Ionic Angular v8 supports Angular versions 16 and above. For detailed information on supported versions and our support policy, see the [Ionic Angular Support Policy](/docs/reference/support#ionic-angular).
+Ionic Angular v9 supports Angular versions 18 through 21. For detailed information on supported versions and our support policy, refer to the [Ionic Angular Support Policy](/docs/reference/support#ionic-angular).
 
 ## Angular Tooling
 

docs/updating/9-0.md

@@ -79,23 +79,6 @@ Remove the `~` prefix from `@ionic/angular` CSS imports. Angular's current build
 + @import '@ionic/angular/css/core.css';
 ```
 
-#### Event Types
-
-The narrow `*CustomEvent` types (such as `RefresherCustomEvent`) are no longer surfaced through Angular template type inference. Use `CustomEvent<*EventDetail>` and cast `event.target` where you call methods on it:
-
-```diff
-- import { RefresherCustomEvent } from '@ionic/angular';
--
-- onRefresh(event: RefresherCustomEvent) {
--   event.target.complete();
-- }
-+ import type { RefresherEventDetail } from '@ionic/core';
-+
-+ onRefresh(event: CustomEvent<RefresherEventDetail>) {
-+   (event.target as HTMLIonRefresherElement | null)?.complete();
-+ }
-```
-
 #### Module Resolution
 
 If your app uses TypeScript `moduleResolution: "node"` (classic), imports from subpaths such as `@ionic/angular/standalone` can fail to resolve. Set `moduleResolution` to `"bundler"` in your `tsconfig.json`. Apps created with `ng new` on Angular 17 or later already use this.