Merge pull request #49088 from xiangpengzhao/get-crd

Automatic merge from submit-queue (batch tested with PRs 48636, 49088, 49251, 49417, 49494)

Add customresourcedefinition and its shortcut in "kubectl get"

**What this PR does / why we need it**:
Add customresourcedefinition and its shortcut in "kubectl get" help info.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #48927

**Special notes for your reviewer**:
/cc @orangedeng 

**Release note**:

```release-note
NONE
```

pkg/kubectl/cmd/cmd.go

@@ -210,6 +210,7 @@ __custom_func() {
     * configmaps (aka 'cm')
     * controllerrevisions
     * cronjobs
+    * customresourcedefinition (aka 'crd')
     * daemonsets (aka 'ds')
     * deployments (aka 'deploy')
     * endpoints (aka 'ep')