'Help' utility

[ChrisPenner]

Both Vim and Emacs have extensive help functionality built into the editor; this has been a great asset for anyone learning the systems and for discoverability of features. Kakoune has even added a 'clippy' like assistant which suggests things as you type!

These are all great things, Rasa has it's own challenges, given that it's a bit more fragmented than other ecosystems we'll need to find a way to allow extensions to extend the documentation, preferably in a way that's searchable or discoverable in some way.

This issue is for discussing possibilities or implementations.