markdown mobx caveat（action.bound）

Posted 2021-05-05

[ref](https://mobx.js.org/refguide/action.html) - bound actions  
use @action.bound for normal function shape
```js
 @action.bound
    increment() {
        this.tick++ // 'this' will always be correct
    }
```

or use below syntax (arrow function)
```js
  @action selectPogyowon = (pogyowon) => {
    this.selectedPogyowon = pogyowon
  }
```