FA模型和stage模型跳转示例代码错误修改，abilityName说明新增，挑单4.0-Beta2

Signed-off-by: Nchenyuyan <chenyuyan3@huawei.com>
Change-Id: I2d3f046d27412b557c945ba6a85d993e2f10a21c

zh-cn/application-dev/application-models/start-pageability-from-stage.md

@@ -8,6 +8,9 @@
 
   UIAbility启动PageAbility和UIAbility启动UIAbility的方式完全相同。
 
+> **说明：**
+> 需注意FA模型中abilityName由bundleName + AbilityName组成，具体见示例。
+
 ```ts
 import UIAbility from '@ohos.app.ability.UIAbility';
 
@@ -25,7 +28,7 @@ export default class EntryAbility extends UIAbility {
         });
         let want = {
             bundleName: "com.ohos.fa",
-            abilityName: "EntryAbility",
+            abilityName: "com.ohos.fa.EntryAbility",
         };
         this.context.startAbility(want).then(() => {
             console.info('Start Ability successfully.');

zh-cn/application-dev/application-models/start-uiability-from-fa.md

@@ -14,7 +14,7 @@ import featureAbility from '@ohos.ability.featureAbility';
 let parameter = {
     "want": {
         bundleName: "com.ohos.stage",
-        abilityName: "com.ohos.stage.EntryAbility"
+        abilityName: "EntryAbility"
     }
 };
 featureAbility.startAbility(parameter).then((code) => {