How are you using Mongo? What version of the server and driver are you using?

Using https://github.com/mongodb/node-mongodb-native through typescript

What is the feauture/improvement you would like?

The signature for `FindCursor<TSchema = Document>` `project` is
 
```

project<T extends Document = Document>(value: Document): FindCursor<T>;

```

I think this should be 

```

project<T extends TSchema>(value: Toggle<T>): FindCursor<T>;

```

where `Toggle<T> = {[keyof T]: 0 | 1}` has the right values.

What use case would this feature/improvement enable?

Better type safety for projections.