[Docs] Update user guide with missing sections

[samccann]

Prerequisites

• [X] This was not already reported in the past (duplicate check)
• [X] It does reproduce it with code from main branch (latest unreleased version)
• [X] I include a minimal example for reproducing the bug
• [X] The bug is not trivial, as for those a direct pull-request is preferred
• [X] Running pip check does not report any conflicts
• [X] I was able to reproduce the issue on a different machine
• [X] The issue is not specific to any driver other than 'default' one

Environment

none

What happened

Documentation is missing sections on:

• Understanding molecule (a section for describing in detail what molecule is and why a user would want to use it)
• How to test collections
• How to test roles within a collection
• How to use molecule with tox-ansible

Reproducing example

No response

[samccann]

See https://ansible.readthedocs.io/projects/project-onboarding/en/latest/docs_toolkit.html for guidelines on recommended documentation for an Ansible project.

[samccann]

User guide structure (in mkdocs.yml) should be something like the following:

• User Guide:
  • user_guide/understanding.md
  • user_guide/testing_collections.md
  • user_guide/testing_roles.md
  • user_guide/ci.md
  • user_guide/using_tox_ansible.md
  • user_guide/examples.md

[Qalthos]

For the time being we should at least hide these entries from being published until they have content to show.

[samccann]

Thanks @Qalthos - they are being removed by https://github.com/ansible/molecule/pull/4044.