Add helper to display language-specific notes

[virtuald]

We can do multiple languages of code like this:

.. tab-set-code::

   .. code-block:: python

Would be useful to be able to specify notes in the same way instead of showing the user notes for all languages.

.. tab-set-note::

   .. note:: python
      Content of note here

[sciencewhiz]

How about

.. tab-set::

   .. tab-item:: python

      .. note:: content of note here