docs(170-validators): begining (not ready)

docs/tutorial/index.rst

@@ -61,5 +61,6 @@ Let's dive into this **configuration options validation** use case.
    multiple
    examples
    practice1
+   validators
    underscore_parameter
    whatsnext

docs/tutorial/validators.rst

@@ -0,0 +1,47 @@
+Validators
+=============
+
+.. objectives:: Objectives
+
+   We will see how to create strong validations for the values ​​of our variables, 
+   that is, validations that go beyond those inherent in the initial type definition.
+
+.. prerequisites:: Prerequisites
+
+    - We assume that Rougail's library is :ref:`installed <installation>` on your computer.
+
+    - It is possible to retrieve the current state of the various Rougail files manipulated in this tutorial step
+      by checking out the corresponding tag of the `rougail-tutorials` git repository.
+      Each tag corresponds to a stage of progress in the tutorial.
+      Of course, you can also decide to copy/paste or download the tutorial files contents while following the tutorial steps.
+
+    If you want to follow this tutorial with the help of the corresponding :tutorial:`rougail-tutorials git repository <src/branch/v1.1>`,
+    this workshop page corresponds to the tag :tutorial:`v1.1_170 <src/tag/v1.1_170/README.md>`
+    in the repository.
+
+    ::
+
+       git clone https://forge.cloud.silique.fr/stove/rougail-tutorials.git
+       git switch --detach v1.1_170
+
+A variable with custom validation
+-----------------------------------
+
+Now, we would like the :term:`operator` to remember not to forget the http protocol, that is to put `http://` at the beginning of our `web_address` variable's value. What if he has forgotten the http protocol? We can add a reminder in case he has forgotten.
+
+We call it a validator.
+
+.. glossary::
+
+   validator
+   
+       A validator is a jinja code that parses a variable's value and checks
+       that this value corresponds to some stated criteria.
+       This is a `validator` parameter of our variable, and another `jinja` sub-parameter
+       contains validation code for the variable's value.
+
+.. extinclude:: https://forge.cloud.silique.fr/stove/rougail-tutorials/raw/commit/v1.1_170/firefox/60-dns_over_https.yml
+   :language: yaml
+   :caption: The :file:`firefox/60-dns_over_https.yml` with the jinja validator
+
+