Update redirects for kubectl commands. (kubernetes#6706)

Author: steveperry-53

_redirects

@@ -340,7 +340,8 @@
 /docs/user-guide/kubeconfig-file/     /docs/tasks/access-application-cluster/authenticate-across-clusters-kubeconfig/ 301
 /docs/user-guide/kubectl-overview/     /docs/reference/kubectl/overview/
 /docs/user-guide/kubectl/     /docs/reference/generated/kubectl/kubectl-options/
-/docs/user-guide/kubectl/v1.8/     /docs/reference/generated/kubectl/kubectl-commands/
+/docs/user-guide/kubectl/v1.8/*     https://v1-8.docs.kubernetes.io/docs/reference/generated/kubectl/kubectl-commands/:splat 301    
+/docs/user-guide/kubectl/v1.9/*     /docs/reference/generated/kubectl/kubectl-commands/:splat 301
 /docs/user-guide/kubectl-conventions/     /docs/reference/kubectl/conventions/
 /docs/user-guide/kubectl-cheatsheet/     /docs/reference/kubectl/cheatsheet/  
 /docs/user-guide/kubectl/1_5/*     https://v1-5.docs.kubernetes.io/docs/user-guide/kubectl/v1.5/ 301