update uikit view documentation (#118715)

* update uikit view documentation

* fix

Author: Chris Yang

packages/flutter/lib/src/rendering/platform_view.dart

@@ -278,13 +278,6 @@ class RenderAndroidView extends PlatformViewRenderBox {
 
 /// A render object for an iOS UIKit UIView.
 ///
-/// {@template flutter.rendering.RenderUiKitView}
-/// Embedding UIViews is still preview-quality. To enable the preview for an iOS app add a boolean
-/// field with the key 'io.flutter.embedded_views_preview' and the value set to 'YES' to the
-/// application's Info.plist file. A list of open issued with embedding UIViews is available on
-/// [Github](https://github.com/flutter/flutter/issues?q=is%3Aopen+is%3Aissue+label%3A%22a%3A+platform-views%22+label%3Aplatform-ios+sort%3Acreated-asc)
-/// {@endtemplate}
-///
 /// [RenderUiKitView] is responsible for sizing and displaying an iOS
 /// [UIView](https://developer.apple.com/documentation/uikit/uiview).
 ///

packages/flutter/lib/src/widgets/platform_view.dart

@@ -202,8 +202,6 @@ class AndroidView extends StatefulWidget {
 // TODO(ychris): remove the documentation for conic path not supported once https://github.com/flutter/flutter/issues/35062 is resolved.
 /// Embeds an iOS view in the Widget hierarchy.
 ///
-/// {@macro flutter.rendering.RenderUiKitView}
-///
 /// Embedding iOS views is an expensive operation and should be avoided when a Flutter
 /// equivalent is possible.
 ///
@@ -216,6 +214,7 @@ class AndroidView extends StatefulWidget {
 /// Construction of UIViews is done asynchronously, before the UIView is ready this widget paints
 /// nothing while maintaining the same layout constraints.
 ///
+/// Clipping operations on a UiKitView can result slow performance.
 /// If a conic path clipping is applied to a UIKitView,
 /// a quad path is used to approximate the clip due to limitation of Quartz.
 class UiKitView extends StatefulWidget {