docs: explain how to get features in Angular

docs/en/UI/Angular/Features.md

@@ -1,3 +1,37 @@
-# Angular UI: Features
+# Features
 
-> This document explains how to get feature values in an Angular application. See the [Features document](../../Features.md) to learn the feature system.
+You can get the value of a feature on the client-side using the [config state service](./Config-State.md) if it is allowed by the feature definition on the server-side.
+
+> This document explains how to get feature values in an Angular application. See the [Features document](../../Features.md) to learn the feature system.
+
+## Before Use
+
+To use the `ConfigStateService`, you must inject it in your class as a dependency. You do not have to provide the service explicitly, because it is already **provided in root**.
+
+```js
+import { ConfigStateService } from '@abp/ng.core';
+
+@Component({
+  /* class metadata here */
+})
+class DemoComponent {
+  constructor(private config: ConfigStateService) {}
+}
+```
+
+## How to Get a Specific Feature
+
+You can use the `getFeature` method of `ConfigStateService` to get a specific feature from the configuration state. Here is an example:
+
+```js
+// this.config is instance of ConfigStateService
+
+const defaultLang = this.config.getFeature("Identity.TwoFactor");
+// 'Optional'
+```
+
+You can then check the value of the feature to perform your logic. Please note that **feature keys are case-sensitive**.
+
+## What's Next?
+
+- [Permission Management](./Permission-Management.md)