Is your feature request related to a problem? Please describe.

I'm always frustrating when, by defining even a relatively small number of collections, I ended up with a gigantic config.yml which is not manageable at all.

Describe the solution you'd like

I'd like to be able to break down config.yml in small pieces (i.e. yml files).

Those yml files could live in a config subdir of static/admin directory. Then NetlifyCMS should be able to merge them all together no matter how deep is the config tree.

Describe alternatives you've considered

The alternative would be to add a step in the build process to create a gigantic yml file composed of the smaller ones.

Additional context

This could be very helpful in migrating data intensive website with a lot of collections (i.e. DB table like structure and relationship).