docs: add rediraffe sphinx extension

This extension helps us restructure our documentation without creating
dead links. It requires us to explicitly declare what should be
redirected where though.

It seems better to have it in place ahead of time than to be something
we ask a contributor add just in time when its needed.

docs/requirements.txt

@@ -18,3 +18,4 @@ sphinx>=4
 sphinx-copybutton
 sphinx-jsonschema
 sphinxext-opengraph
+sphinxext-rediraffe

docs/source/conf.py

@@ -35,6 +35,7 @@ extensions = [
     "sphinx_copybutton",
     "sphinx-jsonschema",
     "sphinxext.opengraph",
+    "sphinxext.rediraffe",
     "myst_parser",
 ]
 root_doc = "index"
@@ -199,3 +200,16 @@ intersphinx_mapping = {
 # ogp_site_url is set automatically by RTD
 ogp_image = "_static/logo.png"
 ogp_use_first_image = True
+
+
+# -- Options for the rediraffe extension -------------------------------------
+# ref: https://github.com/wpilibsuite/sphinxext-rediraffe#readme
+#
+# This extensions help us relocated content without breaking links. If a
+# document is moved internally, a redirect like should be configured below to
+# help us not break links.
+#
+rediraffe_branch = "main"
+rediraffe_redirects = {
+    # "old-file": "new-folder/new-file-name",
+}