Currently, Document conforms to ExpressibleByArrayLiteral. Doing something like
let doc: Document = ["a", "b"]
will create a document in the format in which a BSON array is encoded, ["0": "a", "1": "b"].
However, since the resulting type is a Document, when nested this type is still encoded with the .document subtype, which results in confusion for the user.
We should just remove this initializer altogether. Users can use an [BSON] instead, or create a BSON from an array as BSON conforms to ExpressibleByArrayLiteral.