Enhance docs for DataLoader & django 4.0+ async examples

I went through docs for dataloader & django execution examples, but they seem not working with django 4+ anymore. Django suggests using sync_to_async ( and async_to_sync) wrappers, but I can't wrap my head around that for now. It would be really cool to see some more examples on running django v4 and dataloader (aiodataloader).

**Versions**
```
aiodataloader==0.3.0
Django==4.2b
graphene==3.2
graphene-django==3.0.0
graphene-file-upload==1.3.0
graphql-core==3.2.3
graphql-relay==3.2.0
```

**What I have**

```python
from graphene_django import DjangoObjectType
from aiodataloader import DataLoader

class PhotoFileByImageIdDataLoader(DataLoader):
cache = False

async def batch_load_fn(self, image_ids):
images = Image.objects.filter(id__in=image_ids).select_related("photo_file")

photo_file_by_image_ids = {image.id: image.photo_file for image in images}

return [photo_file_by_image_ids.get(image_id) for image_id in image_ids]

loader = PhotoFileByImageIdDataLoader()

class ImageNode(DjangoObjectType):
...
async def resolve_photo_file(self, *args, **kwargs):
return await loader.load(self.id)
```

What I'm getting after execution:
```json
{
"errors":[
{
"message":"Received incompatible instance \"\".",
"locations":[
{
"line":26,
"column":7
}
],
"path":[
"feed",
"edges",
0,
"node",
"images",
"edges",
0,
"node",
"photoFile"
]
},
...
],
"results": [ ... ]
}
```

Important information: in JSON results, there were results, but photo_file field remains null on each object - that's where the problem is with the `resolve_photo_file` method I suppose.

I followed docs at [https://docs.graphene-python.org/en/latest/execution/dataloader/](https://docs.graphene-python.org/en/latest/execution/dataloader/)

Have anyone stumbled upon something similar? I'm having hard times getting this work