Context

we need to rename variables in DocArray.

Not all of the option are on the table yet but we know that DocumentArray[ImageDoc] is too verbose. We might need to shorten it to DocArray.

We want to find a better name for DocumentArrayStack as well. And maybe introduce a concept of Documents that is a protocol for both DocumentArrayStack and DocumentArray.

DocList could become a replacement name for DocumentArray to be more explicit on what is happening under the hood