message: fix(api): Document deck slot deletion
  Document how to delete labware from a slot to load new labware mid-protocol. A somewhat popular request:
diff: @@ -669,7 +669,15 @@ class ProtocolContext(CommandPublisher):
  is useful for determining if a slot in the deck is free. Rather than
  filtering the objects in the deck map yourself, you can also use
  :py:attr:`loaded_labwares` to see a dict of labwares and
  - :py:attr:`loaded_modules` to see a dict of modules.
  + :py:attr:`loaded_modules` to see a dict of modules. For advanced
  + control you can delete an item of labware from the deck with
  + e.g. ``del protocol.deck['1']`` to free a slot for new labware.
  + (Note that for each slot only the last labware used in a command will
  + be available for calibration in the OpenTrons UI, and that the
  + tallest labware on the deck will be calculated using only currently
  + loaded labware, meaning that the labware loaded should always
  + reflect the labware physically on the deck (or be higher than the
  + labware on the deck).
  """
  return self._deck_layout
  