docs: change class field external link to point to the right page (#5…

…2919)

PR Close #52919

aio/content/guide/what-is-angular.md

@@ -67,9 +67,9 @@ Now that we have the basic structure for the component, let’s learn more about
 
 #### State
 
-When defining data that you want the component to manage, this can be accomplished by declaring it by defining [class fields](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes/Public_class_fields).
+When defining data that you want the component to manage, this can be accomplished by declaring it by defining [class fields](https://www.typescriptlang.org/docs/handbook/2/classes.html#fields).
 
-In the example of a `todo-list-item.component.ts`, there are two properties we want to track: `taskTitle` and `isComplete`. Using the [class field syntax](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes/Public_class_fields), they can be defined as follows:
+In the example of a `todo-list-item.component.ts`, there are two properties we want to track: `taskTitle` and `isComplete`. Using the [class field syntax](https://www.typescriptlang.org/docs/handbook/2/classes.html#fields), they can be defined as follows:
 
 ```ts
 // 📄 todo-list-item.component.ts