Documentation fix, (find returns promises)

I tried to find all occurences when find was used as if it returned a post object and not a promise, but there might be some ones left.

Maybe the lines that look like this: 
```js
store.find('post', 1).then(function (post) {
});
```

Would benefit from some more explanation of the fact that it returns a promise object, but I'm not sure how one would do that.