add header file

Signed-off-by: Nhekun <hekun18@huawei.com>

arkui/ace_ets_component_two/entry/src/main/ets/MainAbility/pages/WaterFlowDataSource.ets

-// 实现IDataSource接口的对象，用于瀑布流组件加载数据
+/**
+ * Copyright (c) 2022 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 export class WaterFlowDataSource implements IDataSource {
 
   private dataArray: number[] = []

arkui/ace_ets_component_two/entry/src/main/ets/MainAbility/pages/WaterflowDemo.ets

-// WaterflowDemo.ets
+/**
+ * Copyright (c) 2022 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 import { WaterFlowDataSource } from './WaterFlowDataSource'
 
 @Entry