Best practices in software engineering

The file index.rst should look like

.. Arrays documentation master file, created by
   sphinx-quickstart on Wed Oct 16 15:33:52 2019.
   You can adapt this file completely to your liking, but it should at least
   contain the root `toctree` directive.

Welcome to Arrays's documentation!
==================================

.. toctree::
   :maxdepth: 2
   :caption: Contents:

This documentation site is all about the arrays module and how to use it.

Indices and tables
==================

* :ref:`genindex`
* :ref:`modindex`
* :ref:`search`

and should create an output like: