Inspector: Add docs for collections

[josephjclark]

The adaptor-docs panel at the moment only shows documentation for the current adaptor (ie, common or http or whatever)

But soon Collections and the Collections API will be available to all adaptors.

We need to work out a way to load the collections API into the list.

[josephjclark]

I suddenly wonder if there's a different concern here.

Rather than documenting collections as its own adaptor, as we do now, should we just append the collections API to every other adaptor?

A bit like how we handle common in other adaptors: