Add docs of app.form.formHost.d.ts

Signed-off-by: Nyanwenhao <yanwenhao9@huawei.com>
Change-Id: Ieff2424659849edc2d74f8ae40a2dae34c1e9914

zh-cn/application-dev/reference/apis/Readme-CN.md

@@ -44,7 +44,7 @@
     - [@ohos.application.errorManager (ErrorManager)](js-apis-errorManager.md)
     - [@oho.app.form.formBindingData (卡片数据绑定类)](js-apis-app-form-formbindingdata.md)
     - [@ohos.application.formError (FormError)](js-apis-formerror.md)
-
+    - [@ohos.app.form.formHost (FormHost)](js-apis-app-form-formhost.md)
     - [@ohos.app.form.formProvider (FormProvider)](js-apis-app-form-formprovider.md)
     - [@ohos.app.form.formInfo (FormInfo)](js-apis-app-form-forminfo.md)
     - [@ohos.application.missionManager (missionManager)](js-apis-missionManager.md)