docs(readme): modify according to standard structure

docs/README.rst

@@ -1,31 +1,66 @@
-===================
+.. _readme:
+
 letsencrypt-formula
 ===================
 
+|img_travis| |img_sr|
+
+.. |img_travis| image:: https://travis-ci.com/saltstack-formulas/letsencrypt-formula.svg?branch=master
+   :alt: Travis CI Build Status
+   :scale: 100%
+   :target: https://travis-ci.com/saltstack-formulas/letsencrypt-formula
+.. |img_sr| image:: https://img.shields.io/badge/%20%20%F0%9F%93%A6%F0%9F%9A%80-semantic--release-e10079.svg
+   :alt: Semantic Release
+   :scale: 100%
+   :target: https://github.com/semantic-release/semantic-release
+
 Creates certificates and manages renewal using the letsencrypt service.
 
-.. image:: https://travis-ci.org/saltstack-formulas/letsencrypt-formula.svg?branch=master
+.. contents:: **Table of Contents**
+
+General notes
+-------------
+
+See the full `SaltStack Formulas installation and usage instructions
+<https://docs.saltstack.com/en/latest/topics/development/conventions/formulas.html>`_.
+
+If you are interested in writing or contributing to formulas, please pay attention to the `Writing Formula Section
+<https://docs.saltstack.com/en/latest/topics/development/conventions/formulas.html#writing-formulas>`_.
+
+If you want to use this formula, please pay attention to the ``FORMULA`` file and/or ``git tag``,
+which contains the currently released version. This formula is versioned according to `Semantic Versioning <http://semver.org/>`_.
 
-.. note::
+See `Formula Versioning Section <https://docs.saltstack.com/en/latest/topics/development/conventions/formulas.html#versioning>`_ for more details.
 
-    See the full `Salt Formulas installation and usage instructions
-    <http://docs.saltstack.com/en/latest/topics/development/conventions/formulas.html>`_.
+If you need (non-default) configuration, please pay attention to the ``pillar.example`` file and/or `Special notes`_ section.
+
+Contributing to this repo
+-------------------------
+
+**Commit message formatting is significant!!**
+
+Please see `How to contribute <https://github.com/saltstack-formulas/.github/blob/master/CONTRIBUTING.rst>`_ for more details.
+
+Special notes
+-------------
+
+None
 
 Available states
-================
+----------------
 
 .. contents::
-    :local:
+   :local:
 
 ``letsencrypt``
----------------
+^^^^^^^^^^^^^^^
 
 This is a shortcut for letsencrypt.install letsencrypt.config and letsencrypt.domains.
 
 If `use_package` is `True` (the default), the formula will try to install the *certbot* package from your Distro's repo.
 Keep in mind that most distros don't have a package available by default: Ie, current Debian (Stretch) requires a backports repo installed.
 Centos 7 requires EPEL, etc. This formula **DOES NOT** manage these repositories. Use the `apt-formula <https://github.com/saltstack-formulas/apt-formula>`_
-or the `epel-formula <https://github.com/saltstack-formulas/epel-formula`_ to manage them.
+or the `epel-formula <https://github.com/saltstack-formulas/epel-formula>`_ to manage them.
 
 If `use_package` is `False` it installs and configures the letsencrypt cli from git, creates the requested certificates and installs renewal cron job.
 
@@ -37,23 +72,67 @@ If you set `use_package` to `True`, it will:
   systemd's timer unit to renew all the certs)
 * Delete git-based installation's scripts (usually installed under /usr/local/bin) if they still exist declared in
   *letsencrypt*'s pillar.
-* As a safety meassure, if there's an /opt/letsencrypt directory from a git-based installation, it will be left
+* As a safety measure, if there's an /opt/letsencrypt directory from a git-based installation, it will be left
   untouched, but unused.
 To check dependencies to use the package for your distro, check https://certbot.eff.org/all-instructions.
 
 ``letsencrypt.install``
------------------------
+^^^^^^^^^^^^^^^^^^^^^^^
 
 Only installs the letsencrypt client (see above).
 
 ``letsencrypt.config``
-----------------------
+^^^^^^^^^^^^^^^^^^^^^^
 
 Manages /etc/letsencrypt/cli.ini config file.
 
 ``letsencrypt.domains``
------------------------
+^^^^^^^^^^^^^^^^^^^^^^^
 
 Creates a certificate with the domains in each domain set (letsencrypt:domainsets in pillar). Letsencrypt uses a relatively short validity of 90 days.
 Therefore, a cron job for automatic renewal every 60 days is installed for each domain set as well.
 
+Testing
+-------
+
+Linux testing is done with ``kitchen-salt``.
+
+Requirements
+^^^^^^^^^^^^
+
+* Ruby
+* Docker
+
+.. code-block:: bash
+
+   $ gem install bundler
+   $ bundle install
+   $ bin/kitchen test [platform]
+
+Where ``[platform]`` is the platform name defined in ``kitchen.yml``,
+e.g. ``debian-9-2019-2-py3``.
+
+``bin/kitchen converge``
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+Creates the docker instance and runs the ``template`` main state, ready for testing.
+
+``bin/kitchen verify``
+^^^^^^^^^^^^^^^^^^^^^^
+
+Runs the ``inspec`` tests on the actual instance.
+
+``bin/kitchen destroy``
+^^^^^^^^^^^^^^^^^^^^^^^
+
+Removes the docker instance.
+
+``bin/kitchen test``
+^^^^^^^^^^^^^^^^^^^^
+
+Runs all of the stages above in one go: i.e. ``destroy`` + ``converge`` + ``verify`` + ``destroy``.
+
+``bin/kitchen login``
+^^^^^^^^^^^^^^^^^^^^^
+
+Gives you SSH access to the instance for manual testing.