[IMP] contributing/doc, install: add an extension for content tabs

In many places in the docs, we need to document several flows that
differ only by a few details. For example, the steps to install Odoo
from the sources are almost identical for Windows, Linux, and Mac OS.
In other places, we'd want to suggest a command in different
environments or programming languages, etc.

This commit thus adds an extension for content tabs (tabs within the
content) to help reduce content repetition in the documentation. As a
proof of concept, the "Packaged installers" and "Source install"
sections of the "Installing Odoo" page are reworked to present their
content within tabs whenever it helps clarify the instructions.

A new python dependency is added as of this commit: `sphinx-tabs`

task-2713983

closes odoo/documentation#1528

Signed-off-by: Antoine Vandevenne (anv) <anv@odoo.com>
Co-authored-by: Lucie Van Nieuwenhuyse (luvn) <luvn@odoo.com>

conf.py

@@ -124,9 +124,13 @@ extensions = [
     # Code switcher (switcher and case directives)
     'switcher',
 
+    # Content tabs
+    'sphinx_tabs.tabs',
+
     # Strange html domain logic used in memento pages
     'html_domain',
 ]
+
 if odoo_dir_in_path:
     # GitHub links generation
     extensions += [
@@ -167,6 +171,9 @@ supported_languages = {
 # The specifications of redirect rules used by the redirects extension.
 redirects_file = 'redirects.txt'
 
+sphinx_tabs_disable_tab_closing = True
+sphinx_tabs_disable_css_loading = False
+
 #=== Options for HTML output ===#
 
 html_theme = 'odoo_theme'

content/administration/install.rst

@@ -4,6 +4,8 @@
 Install
 =======
 
+.. If you add content on this page, remove the redirect rule 'install -> install/install'
+
 .. toctree::
 
     install/install

content/contributing/documentation/rst_cheat_sheet.rst

@@ -521,6 +521,219 @@ Render
 
    Customize this admonition with a **Title** of your choice.
 
+.. _contributing/tabs:
+
+Content tabs
+============
+
+.. caution::
+   The `tabs` directive may not work well in some situations. In particular:
+
+   - The tabs' headers cannot be translated.
+   - A tab cannot contain :ref:`headings <contributing/headings>`.
+   - An :ref:`admonition <contributing/admonitions>` cannot contain tabs.
+   - A tab cannot contain :ref:`internal hyperlink targets
+     <contributing/internal-hyperlink-targets>`.
+
+Basic tabs
+----------
+
+RST
+~~~
+
+.. code-block:: rst
+
+   .. tabs::
+
+      .. tab:: Odoo Online
+
+         Content dedicated to Odoo Online users.
+
+      .. tab:: Odoo.sh
+
+         Alternative for Odoo.sh users.
+
+      .. tab:: On-premise
+
+         Third version for On-premise users.
+
+Render
+~~~~~~
+
+.. tabs::
+
+   .. tab:: Odoo Online
+
+      Content dedicated to Odoo Online users.
+
+   .. tab:: Odoo.sh
+
+      Alternative for Odoo.sh users.
+
+   .. tab:: On-premise
+
+      Third version for On-premise users.
+
+Nested tabs
+-----------
+
+RST
+~~~
+
+.. code-block:: rst
+
+   .. tabs::
+
+      .. tab:: Stars
+
+         .. tabs::
+
+            .. tab:: The Sun
+
+               The closest star to us.
+
+            .. tab:: Proxima Centauri
+
+               The second closest star to us.
+
+            .. tab:: Polaris
+
+               The North Star.
+
+      .. tab:: Moons
+
+         .. tabs::
+
+            .. tab:: The Moon
+
+               Orbits the Earth.
+
+            .. tab:: Titan
+
+               Orbits Jupiter.
+
+Render
+~~~~~~
+
+.. tabs::
+
+   .. tab:: Stars
+
+      .. tabs::
+
+         .. tab:: The Sun
+
+            The closest star to us.
+
+         .. tab:: Proxima Centauri
+
+            The second closest star to us.
+
+         .. tab:: Polaris
+
+            The North Star.
+
+   .. tab:: Moons
+
+      .. tabs::
+
+         .. tab:: The Moon
+
+            Orbits the Earth.
+
+         .. tab:: Titan
+
+            Orbits Jupiter.
+
+Group tabs
+----------
+
+RST
+~~~
+
+.. code-block:: rst
+
+   .. tabs::
+
+      .. group-tab:: C++
+
+         C++
+
+      .. group-tab:: Python
+
+         Python
+
+      .. group-tab:: Java
+
+         Java
+
+   .. tabs::
+
+      .. group-tab:: C++
+
+         .. code-block:: c++
+
+            int main(const int argc, const char **argv) {
+                return 0;
+            }
+
+      .. group-tab:: Python
+
+         .. code-block:: python
+
+            def main():
+                return
+
+      .. group-tab:: Java
+
+         .. code-block:: java
+
+            class Main {
+                public static void main(String[] args) {}
+            }
+
+Render
+~~~~~~
+
+.. tabs::
+
+   .. group-tab:: C++
+
+      C++
+
+   .. group-tab:: Python
+
+      Python
+
+   .. group-tab:: Java
+
+      Java
+
+.. tabs::
+
+   .. group-tab:: C++
+
+      .. code-block:: c++
+
+         int main(const int argc, const char **argv) {
+             return 0;
+         }
+
+   .. group-tab:: Python
+
+      .. code-block:: python
+
+         def main():
+             return
+
+   .. group-tab:: Java
+
+      .. code-block:: java
+
+         class Main {
+             public static void main(String[] args) {}
+         }
+
 .. _contributing/document-metadata:
 
 Document metadata

content/developer/howtos/rdtraining/02_setup.rst

@@ -184,7 +184,7 @@ You can check your Python version with:
 Install required packages
 -------------------------
 
-See :ref:`install/python-dependencies`
+See :ref:`install/dependencies`.
 
 .. _howto/rdtraining/02_setup/install-wkhtmltopdf:
 

requirements.txt

@@ -2,4 +2,5 @@ libsass==0.18.0
 pygments~=2.6.1
 pygments-csv-lexer~=0.1
 sphinx~=3.0
+sphinx-tabs~=3.2.0
 werkzeug==0.14.1