docs: add an extension to generate redirects

Reviewed-by: Eric Engestrom <eric@engestrom.ch>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5706>
diff --git a/docs/conf.py b/docs/conf.py
index 2736765..5661fe0 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -38,7 +38,7 @@
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
-extensions = ['sphinx.ext.graphviz', 'formatting']
+extensions = ['sphinx.ext.graphviz', 'formatting', 'redirects']
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']