This directory of templates  (pointed to by conf.py) customizes how sphinx
autosummary populates the the sphinx-built documentation. The autosummary 
directives are chiefly used within our api_refernce.rst documentation source
file. The directory can contain any of the following restructured text files that describe to
 sphinx-autodoc how to format the sphinx-produced reference docs:

   class.rst
   function.rst
   attribute.rst
   method.rst
   module.rst
   base.rst  -- a fallback template

These templates tell autosummary how to populate so-called "stub" files with autodoc
directives (e.g. ".. autoclass ::" , or ".. automethod ::".) [1]_, [2]_. In turn, these
autodoc directives import documentation text from the source code.

The default templates used by autosummary to populate "stub" files can be found within
a given sphinx installation at:
".../lib/pythonX.X/site-packages/sphinx/ext/autosummary/templates/autosummary".
Further, the pandas package (just an exemplary open-source package with extensive docs)
has its autosummary templates published in [3]_. Experimenting/building with these  
default templates provide a practical introduction to jinja templating, autosummary, AND
autodocs.

Sources: 
   .. [1] sphinx autodoc -- populates documentation using docstrings from source code with `auto...` 
   reST directives  (e.g. autoclass, automodule, automethod)
   https://www.sphinx-doc.org/en/master/usage/extensions/autodoc.html#module-sphinx.ext.autodoc

   .. [2] sphinx autosummary -- Enables 'autosummary' reST directive that can create table-of-contents 
   entries from source code object references AND auto populate link targets (so-called stub files) 
   using autodoc directives. (Autodoc directives generated by autosummary can be customized with 
   templates in the jinja syntax.)
   https://www.sphinx-doc.org/en/master/usage/extensions/autosummary.html#customizing-templates

   .. [3] Autosummary templates used by pandas: 
   https://github.com/pandas-dev/pandas/tree/main/doc/_templates/autosummary