Add support for sub-modules in autosummary

[gregory-shklover]

Subject: Adds support for "modules" template argument so one can generate recursive documentation.

Feature or Bugfix

• Feature

Purpose

Adds support for generating recursive module documentation. For each module, documents imported sub-modules and adds corresponding "modules" template parameter. The parameter can be used in a module template like this: ... .. automodule:: {{ fullname }}

 {% block modules %}
 {% if modules %}
 .. rubric:: Modules

 .. autosummary::
    :toctree: {{ name }}
 {% for item in modules %}
    {{ item }}
 {%- endfor %}
 {% endif %}
 {% endblock %}

...

Detail

Relates

[gregory-shklover]

Converted to "draft" to resolve differences vs ":recursive:" feature in autosummary.