[ADD] tutorials/website_theme: Add tutorials to build a website theme

closes odoo/documentation#13202

Signed-off-by: Antoine Vandevenne (anv) <anv@odoo.com>
Signed-off-by: Céline de Lannoy (cede) <cede@odoo.com>

content/developer/tutorials/website_theme.rst

@@ -0,0 +1,54 @@
+:show-content:
+:show-toc:
+:hide-page-toc:
+
+=====================
+Build a website theme
+=====================
+
+| For this project, we'll collaborate on creating a custom website theme fully integrated with Odoo.
+| Our client, Airproof, has provided their latest design for their waterproof drone e-commerce,
+  which we'll replicate.
+
+To start, you must have :doc:`installed Odoo locally </administration/on_premise/source>`.
+You will also need some knowledge in:
+
+- XML
+- JavaScript (not mandatory)
+- Bootstrap 5.1.3
+- SCSS
+- QWeb (Odoo's own templating system)
+- OWL (JavaScript framework, not mandatory)
+
+| **Goal**
+| Replicate the Airproof design.
+
+.. image:: website_theme/airproof-home.png
+   :alt: Airproof homepage.
+   :align: center
+
+| In the :file:`README.md` of the `Airproof module <{GITHUB_TUTO_PATH}/website_airproof>`_, you can
+  find the various Airproof designs that you will replicate throughout the different exercises in
+  this tutorial.
+| You can also find all the code necessary for creating the Airproof website there. You should also
+  obtain this by the end of the tutorial. It is recommended to try solving the exercices first
+  without looking at the solution!
+
+| **Don't go too fast!**
+| Follow the exercises step by step and you will reach the final design at the end of the tutorial.
+
+Throughout this tutorial, you will find "See also" sections leading to parts of the :doc:`How-to
+guide: Website themes <../howtos/website_themes>` documentation. Be sure to read this documentation
+thoroughly each time! With it, you will find the solution to every exercise.
+
+Ready? Let's get started!
+
+.. toctree::
+    :maxdepth: 2
+
+    website_theme/01_theming
+    website_theme/02_build_website
+    website_theme/03_customisation_part1
+    website_theme/04_customisation_part2
+    website_theme/05_dynamic_templates
+    website_theme/06_going_live