chore(docs): Another fix for redirects command

Author: tony

docs/Makefile

@@ -155,7 +155,7 @@ doctest:
 	      "results in $(BUILDDIR)/doctest/output.txt."
 
 redirects:
-	$(SPHINXBUILD) -b rediraffewritediff $(ALLSPHINXOPTS)
+	$(SPHINXBUILD) -b rediraffewritediff $(ALLSPHINXOPTS) $(BUILDDIR)/redirects
 	@echo
 	@echo "Build finished. The redirects are in rediraffe_redirects."