Mention grouping sphinx object definitions

[nineteendo]

Describe the enhancement or feature you'd like

Could we mention how to group sphinx object definitions?

.. data:: ParamSpecArgs
          ParamSpecKwargs

Additional context

• python/cpython#118030
• https://discuss.python.org/t/grouping-sphinx-object-definition-directives/52745

[hugovk]

For reference, PR: #1322

Let's close this issue, we already have a CPython issue and discuss thread, and now PR.