Notebooks: folder structure for organization

It would really help us out if we could organize our Terra notebooks using a file folder structure within our workspace.

Once we get a lot of notebooks saved (and we use them for development too, not just polished end products), the main notebook screen is a mess, and it is very difficult to find notebooks we're looking for.

We would love the ability to organize the notebooks within our workspace using named folders, just like on a local machine.

Thanks!