Merge pull request kubernetes#52786 from yujunz/fix-url

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>..

Fix url for Saltstack administration document

Got an 404 not found error on `https://kubernetes.io/docs/admin/salt.md`



**What this PR does / why we need it**:

Fixed a wrong url in document

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #

**Special notes for your reviewer**:

NONE

**Release note**:

```release-note
NONE
```

cluster/saltbase/README.md

@@ -1,7 +1,7 @@
 # SaltStack configuration
 
 This is the root of the SaltStack configuration for Kubernetes. A high
-level overview for the Kubernetes SaltStack configuration can be found [in the docs tree.](https://kubernetes.io/docs/admin/salt.md)
+level overview for the Kubernetes SaltStack configuration can be found [in the docs tree.](https://kubernetes.io/docs/admin/salt/)
 
 This SaltStack configuration currently applies to default
 configurations for Debian-on-GCE, Fedora-on-Vagrant, Ubuntu-on-AWS and