IssueNo: #I7X5WW:[新需求]: Rectify the arkts syntax of qs on monthly

Description: Rectify the arkts syntax of qs on monthly
Sig: SIG_ApplicaitonFramework
Feature or Bugfix: Feature
Binary Source: No
Signed-off-by: N189******51 <lipeicheng5@huawei.com>

zh-cn/application-dev/quick-start/arkts-prop.md

@@ -118,7 +118,7 @@ this.title.push('3')
 ```ts
 @Component
 struct DateComponent {
-  @Prop selectedDate: Date;
+  @Prop selectedDate: Date = new Date('');
 
   build() {
     Column() {
@@ -198,7 +198,7 @@ ParentComponent的状态变量countDownStartValue的变化将重置CountDownComp
 ```ts
 @Component
 struct CountDownComponent {
-  @Prop count: number;
+  @Prop count: number = 0;
   costOfOneAttempt: number = 1;
 
   build() {
@@ -370,7 +370,7 @@ class Book {
 
 @Component
 struct ReaderComp {
-  @Prop book: Book;
+  @Prop book: Book = new Book("", 0);
 
   build() {
     Row() {
@@ -497,7 +497,7 @@ class Book {
 ```ts
 @Component
 struct MyComponent {
-  @Prop customCounter: number;
+  @Prop customCounter: number = 0;
   @Prop customCounter2: number = 5;
 
   build() {