Update TODO now that initial round selection is available
One TODO item is clearly complete here: The new multi-select field in
the modal form when creating a puzzle. That's working well enough that
I don't think we need the separate /round command so I'm dropping that
from the TODO.
Two little things are needed to really make round support complete:
* Display/grouping of rounds in the Turbot home view
* Select same rounds (by default) when creating a new puzzle in the
same channel of an existing channel