(DOCSP-12607): fix redirects

Author: jwilliams-mongo

config/redirects

@@ -53,4 +53,7 @@ raw: kubernetes-operator/release-notes -> ${base}/stable/release-notes
 [*-v1.3]: kubernetes-operator/${version}/tutorial/modify-resource-image -> ${base}/${version}/
 
 # v1.7 and later
-[v1.7-*]: kubernetes-operator/${version}/tutorial/upgrade-k8s-operator-v9-and-earlier -> kubernetes-operator/${version}/tutorial/upgrade-k8s-operator-v161-and-earlier
+[v1.7-*]: kubernetes-operator/${version}/tutorial/upgrade-k8s-operator-v9-and-earlier -> ${base}/${version}/tutorial/upgrade-k8s-operator-v161-and-earlier
+
+# v1.8 and later
+[v1.8-*]: kubernetes-operator/${version}/tutorial/upgrade-k8s-operator-v161-and-earlier -> ${base}/${version}/tutorial/upgrade-k8s-operator