doc: add download badge on index page

Author: xdelaruelle

doc/source/index.rst

@@ -7,9 +7,13 @@ Environment Modules
     :target: https://github.com/cea-hpc/modules
     :alt: GitHub Repository
 
-.. image:: https://img.shields.io/github/license/cea-hpc/modules
+.. image:: https://img.shields.io/github/license/cea-hpc/modules?color=lightsteelblue
     :alt: GitHub License
 
+.. image:: https://img.shields.io/github/v/release/cea-hpc/modules
+    :target: https://github.com/cea-hpc/modules/releases/latest
+    :alt: GitHub Release
+
 .. image:: https://img.shields.io/twitter/url/https/twitter.com/EnvModules.svg?style=social&label=@EnvModules
     :target: https://twitter.com/EnvModules
     :alt: Twitter/X