Update urls to 1.7 (#4276)

* assign-pod-node.md

* secret.md

* kubernetes-objects.md

* service.md

docs/concepts/configuration/secret.md

@@ -124,7 +124,7 @@ The data field is a map.  Its keys must match
 [`DNS_SUBDOMAIN`](https://git.k8s.io/community/contributors/design-proposals/identifiers.md), except that leading dots are also
 allowed.  The values are arbitrary data, encoded using base64.
 
-Create the secret using [`kubectl create`](/docs/user-guide/kubectl/v1.6/#create):
+Create the secret using [`kubectl create`](/docs/user-guide/kubectl/v1.7/#create):
 
 ```shell
 $ kubectl create -f ./secret.yaml