docs: Add config for redirecting pages.

We want to be able to move pages around and have sphinx automatically
redirect to the now location when that happens.  This will allow us to
re-organize safely as we figure out the best way to layout the
documentation.

docs/guides/Makefile

@@ -20,3 +20,11 @@ clean:
 # "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
 %: Makefile
 	$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
+
+update_redirects:
+	# This updates redirects.txt, creating redirects for any files that have moved (relative to master).
+	sphinx-build -b rediraffewritediff "$(SOURCEDIR)" "$(BUILDDIR)"
+
+check_redirects:
+	# Check to make sure that any files that got moved have a redirect in redirects.txt
+	sphinx-build -b rediraffecheckdiff "$(SOURCEDIR)" "$(BUILDDIR)"

docs/guides/conf.py

@@ -62,11 +62,16 @@ extensions = [
     'sphinx.ext.mathjax',
     'sphinx.ext.napoleon',
     'sphinxcontrib.openapi',
+    'sphinxext.rediraffe',
     'sphinx_design',
     'code_annotations.contrib.sphinx.extensions.featuretoggles',
     'code_annotations.contrib.sphinx.extensions.settings',
 ]
 
+# Rediraffe related settings.
+rediraffe_redirects = "redirects.txt"
+rediraffe_branch = 'origin/master'
+
 # code_annotations.(featuretoggles|settings) related settings.
 edxplatform_repo_url = "https://github.com/openedx/edx-platform"
 edxplatform_source_path = os.path.abspath(