Please add the documentation for Group

[DenisMondon]

Hi!

Please can you add Group (android.support.constraint.Group) in your documentation?
Here is a Medium link: https://medium.com/@rafael_toledo/whats-new-in-constraint-layout-1-1-x-f0bdd4dbdfb3

Thanks a lot :)
Denis

[rock3r]

Hey Denis, sorry this took forever but we've all been very busy! Sure this is a good request, we're currently waiting to see what's new in CL 2.0 before we write new material, so it won't happen any time soon, but we hope we'll be able to improve and expand the material at that point.