docs: add override i18n configuration

docs/i18n.en-US.md

@@ -157,3 +157,28 @@ registerLocaleData(en);
 
 [https://date-fns.org/docs/I18n#supported-languages](https://date-fns.org/docs/I18n#supported-languages)
 
+## How to override internationalization configuration
+The text of some components in `ng-zorro` depends on the internationalized text, such as the `size changer` in `nz-pagination`. At this time, you can modify the internationalization configuration to change the text content in the `size changer`:
+
+``` typescript
+
+import { NZ_I18N, en_US } from 'ng-zorro-antd/i18n';
+
+const customLanguagePack = {
+  en_US,
+  ...{
+    Pagination: {
+      items_per_page: "per page"
+    }
+  }
+}
+
+@NgModule({
+  ...
+  providers   : [
+    { provide: NZ_I18N, useValue: customLanguagePack }
+  ]
+})
+export class AppModule { }
+
+```

docs/i18n.zh-CN.md

@@ -154,3 +154,29 @@ registerLocaleData(en);
 ## date-fns 支持语言
 
 [https://date-fns.org/docs/I18n#supported-languages](https://date-fns.org/docs/I18n#supported-languages)
+
+## 如何更改默认国际化语言包配置
+`ng-zorro` 中有些组件的文本依赖于国际化文本，例如 `nz-pagination` 中的 `size changer`, 这时候你可以修改国际化配置来更改 `size changer` 中的文本内容：
+
+``` typescript
+
+import { NZ_I18N, en_US } from 'ng-zorro-antd/i18n';
+
+const customLanguagePack = {
+  en_US,
+  ...{
+    Pagination: {
+      items_per_page: "per page"
+    }
+  }
+}
+
+@NgModule({
+  ...
+  providers   : [
+    { provide: NZ_I18N, useValue: customLanguagePack }
+  ]
+})
+export class AppModule { }
+
+```