Add mention about reactive() and Vue 3

 In version 3.0 you can create a reactive object with the reactive() API. ```javascript const reactiveState = reactive({ count: 0 }) ```

Author: w3bdesign

README.md

@@ -4202,7 +4202,13 @@ List of 300 VueJS Interview Questions
  **[⬆ Back to Top](#table-of-contents)**
 
 197. ### How do you create reactive objects?
- From 2.6 version onwards, you can create reactive objects with Vue.observable() global API.
+ In version 3.0 you can create a reactive object with the reactive() API.
+ ```javascript
+ const reactiveState = reactive({
+ count: 0
+ })
+ ```
+ In version 2.6, you can create reactive objects with Vue.observable() global API.
  ```javascript
  const reactiveState = Vue.observable({
  count: 0