doc: adapt index for non-html output

Only generate images at the top for html output. Move TOC tree
definition at the end and use it only on html output. Adapt section
underlining to cope with sourcing of this document into another.

Signed-off-by: Xavier Delaruelle <[email protected]>

Author: xdelaruelle

doc/source/index.rst

@@ -3,25 +3,26 @@
 Environment Modules
 ===================
 
-.. image:: https://img.shields.io/github/stars/envmodules/modules
-    :target: https://github.com/envmodules/modules
-    :alt: GitHub Repository
+.. only:: html
 
-.. image:: https://img.shields.io/github/license/envmodules/modules?color=lightsteelblue
-    :alt: GitHub License
+   .. image:: https://img.shields.io/github/stars/envmodules/modules
+      :target: https://github.com/envmodules/modules
+      :alt: GitHub Repository
 
-.. image:: https://img.shields.io/github/v/release/envmodules/modules
-    :target: https://github.com/envmodules/modules/releases/latest
-    :alt: GitHub Release
+   .. image:: https://img.shields.io/github/license/envmodules/modules?color=lightsteelblue
+      :alt: GitHub License
 
-.. image:: https://img.shields.io/badge/dynamic/json?url=https%3A%2F%2Fpublic.api.bsky.app%2Fxrpc%2Fapp.bsky.actor.getProfile%2F%3Factor%3Denvmodules.bsky.social&query=%24.followersCount&style=social&logo=bluesky&label=%40EnvModules
-    :target: https://bsky.app/profile/envmodules.bsky.social
-    :alt: Bluesky
+   .. image:: https://img.shields.io/github/v/release/envmodules/modules
+      :target: https://github.com/envmodules/modules/releases/latest
+      :alt: GitHub Release
 
-.. image:: https://img.shields.io/matrix/modules%3Amatrix.org?color=darkcyan
-   :target: https://matrix.to/#/#modules:matrix.org
-   :alt: Matrix
+   .. image:: https://img.shields.io/badge/dynamic/json?url=https%3A%2F%2Fpublic.api.bsky.app%2Fxrpc%2Fapp.bsky.actor.getProfile%2F%3Factor%3Denvmodules.bsky.social&query=%24.followersCount&style=social&logo=bluesky&label=%40EnvModules
+      :target: https://bsky.app/profile/envmodules.bsky.social
+      :alt: Bluesky
 
+   .. image:: https://img.shields.io/matrix/modules%3Amatrix.org?color=darkcyan
+      :target: https://matrix.to/#/#modules:matrix.org
+      :alt: Matrix
 
 **Welcome to the Environment Modules documentation portal. The Environment
 Modules package provides for the dynamic modification of a user's environment
@@ -55,7 +56,7 @@ different applications.
    capabilities to scripts.
 
 Quick examples
---------------
+^^^^^^^^^^^^^^
 
 Here is an example of loading a module on a Linux machine under bash.
 ::
@@ -88,51 +89,8 @@ Now we'll log into a different machine, using a different shell (tcsh).
 Note that the command line is exactly the same, but the path has
 automatically configured to the correct architecture.
 
-.. toctree::
-   :hidden:
-   :maxdepth: 2
-   :caption: Basics
-
-   INSTALL
-   INSTALL-win
-   MIGRATING
-   NEWS
-   FAQ
-   changes
-   other-implementations
-
-.. toctree::
-   :hidden:
-   :maxdepth: 2
-   :caption: Examples
-
-   cookbook
-
-.. toctree::
-   :hidden:
-   :maxdepth: 2
-   :caption: Reference
-
-   ml
-   module
-   modulefile
-   envml
-
-.. toctree::
-   :hidden:
-   :maxdepth: 2
-   :caption: Development
-
-   CONTRIBUTING
-   devel
-   design
-   CHARTER
-   GOVERNANCE
-   acknowledgments
-
-
 Get started with Modules
-------------------------
+^^^^^^^^^^^^^^^^^^^^^^^^
 
 Learn how to retrieve and install Modules :ref:`on Unix<INSTALL>` or
 :ref:`on Windows<INSTALL-win>`. An overlook on the new functionalities
@@ -150,7 +108,7 @@ Modules and how to extend the :command:`module` command to achieve specific
 needs.
 
 Links
------
+^^^^^
 
 * Web site: https://envmodules.io
 * Documentation: https://modules.readthedocs.io
@@ -161,7 +119,7 @@ Links
 .. _Community:
 
 Community
----------
+^^^^^^^^^
 
 Modules is an open source project. Questions, discussion, and contributions
 are welcome. You can get in contact with the Modules community via:
@@ -183,7 +141,7 @@ The project is also present on several social media platforms:
 .. _@EnvModules.bsky.social: https://bsky.app/profile/envmodules.bsky.social
 
 Contributing
-------------
+^^^^^^^^^^^^
 
 Modules project welcomes contributions of all kinds! Before submitting an
 issue or pull request, please take a moment to review our :ref:`Contributing
@@ -197,7 +155,7 @@ the Modules community, you agree to abide by its rules.
 .. _Code of conduct: https://github.com/envmodules/modules?tab=coc-ov-file#readme
 
 Governance
-----------
+^^^^^^^^^^
 
 Modules is part of the `High Performance Software Foundation`_ within the
 `Linux Foundation`_.
@@ -209,7 +167,51 @@ governance model, decision-making process, and long-term vision.
 .. _Linux Foundation: http://linuxfoundation.org
 
 License
--------
+^^^^^^^
 
 Modules is distributed under the GNU General Public License, either version 2
 or (at your option) any later version (`GPL-2.0-or-later`).
+
+.. only:: html
+
+   .. toctree::
+      :hidden:
+      :maxdepth: 2
+      :caption: Basics
+
+      INSTALL
+      INSTALL-win
+      MIGRATING
+      NEWS
+      FAQ
+      changes
+      other-implementations
+
+   .. toctree::
+      :hidden:
+      :maxdepth: 2
+      :caption: Examples
+
+      cookbook
+
+   .. toctree::
+      :hidden:
+      :maxdepth: 2
+      :caption: Reference
+
+      ml
+      module
+      modulefile
+      envml
+
+   .. toctree::
+      :hidden:
+      :maxdepth: 2
+      :caption: Development
+
+      CONTRIBUTING
+      devel
+      design
+      CHARTER
+      GOVERNANCE
+      acknowledgments