When a user specifies a depth to be collapsed, the intention is to make the JSON tidy so it is easy to visually parse.

Currently the `deep` prop only collapses at the specific level passed, and when a user opens that depth, all children are fully open.

I think this should collapse all children beyond the depth level, so that when the items are opened up the children are collapsed.

That said, for backwards compatibility I've implemented this as a new prop, defaulting to false, so that anyone upgrading won't see a change in behaviour.

Let the user know about the new prop for collapsing all children at the level below the `deep` prop passed.

This is a new option provided for collapsing children inside those
collapsed by default, so is exposed here