Lesson 2 (chapter 3) Castle Duel - bug in book - missing can-play class during dev

## What is happening:
During the second project (chapter 3) Castle Duel, as you are going through the chapter, the `hand` is not clickable, making much of the work untestable, leading readers (myself included) believing that our @click or method is broken somehow leading to much frustration during this lesson.

## What I think should be happening?
Where the reader makes the createTestHand and a testPlayCard methods in the main.js, have them also add `this.canPlay = true` into the created lifecycle hook of the main.js Vue component and have the reader apply the computed cssClass for can-play earlier in the chapter.

```
created () {
this.testHand = this.createTestHand()
this.canPlay = true
},
computed: {
cssClass () {
return {
'can-play': this.canPlay,
}
},
},
```

I was able to track how to fix this by reading through style.less where I saw that pointer-events is, in fact, set to none by default for `.hand`. It then gets update to `pointer-events: all;` when the `.can-play` class gets applied. Applied it by hand (like above) and I can now test the transitions and @click events as expected.