trello-clone.md missing imports

https://github.com/flet-dev/website/blob/main/docs/tutorials/trello-clone.md

I think `app_layout.py` is missing:

``` python
from flet.core.control import Control
```

due to the line

```
        self._active_view: Control = ft.Column(
```

Also, `Sidebar.py` contains the line:
```python
    def __init__(self, app_layout, store: DataStore):
```
I've no clue what DataStore is?