Allow nested folder structure

[ttomdewit]

Hi 👋 ,

I think this project has a lot of promise and I'm looking forward to using it in the future. However, having tested this just now, I think it'll worthwhile to automatically support a nested structure.

I've followed the example in the README.md file but wasn't able to build the static HTML pages. Would it be at all in the scope of this project to allow for a structure similar to the following:

root
- features
- - feature name 1
- - - create.feature
- - - update.feature
- - feature name 2
- - - create.feature
- - - update.feature
- - - delete.feature
- - feature name 3
- - - create.feature
- - - update.feature
- - - delete.feature
- - - deactivate.feature

It would be perfect if the output would respect the aforementioned structure and create the static HTML files within the sub-folders.

If I'm already able to achieve the above, please don't mind this issue!

--
Kind regards,

Tom