Merge pull request kubernetes#48665 from praseodym/add-short-names-help-text

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>.

Add missing short names to kubectl help text

**What this PR does / why we need it**:
This PR adds two short names that exist but are not listed in the help text that `kubectl get` produces.

**Special notes for your reviewer**:
🍰 

**Release note**:
```release-note
NONE
```

Author: Kubernetes Submit Queue

pkg/kubectl/cmd/cmd.go

@@ -242,8 +242,8 @@ __custom_func() {
     * secrets
     * serviceaccounts (aka 'sa')
     * services (aka 'svc')
-    * statefulsets
-    * storageclasses
+    * statefulsets (aka 'sts')
+    * storageclasses (aka 'sc')
 
 `
 )