Add boundary check functions to region guide

```js
const door = canvas.walls.doors.find(e => region.object.testPoint({x: e.document.c[0], y: e.document.c[1]}) || region.object.testPoint({x: e.document.c[2], y: e.document.c[3]})); // check if the amount of ) is correct here :D
```
Region document, which should contain a Set of the tokens within it. so a simple check for

```js
const amountTokens = region.tokens.size;
// do something with amountTokens
```

The triggered macro or script has the Region document defined as `region` in it arguments so you can just use that.