Merge pull request #59030 from flonn/fix_typo_help

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>.

typo fix in 'kubectl run'´s help

**What this PR does / why we need it**:
fix typo in cmd help
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #

**Special notes for your reviewer**:

**Release note**:

```release-note

```
This commit is contained in:
Kubernetes Submit Queue 2018-08-06 11:48:56 -07:00 committed by GitHub
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