Automatic merge from submit-queue (batch tested with PRs 50023, 50639)
Correct case for starting character of option string
**What this PR does / why we need it**:
Kubectl-conventions.md states:
"Flag descriptions should start with an uppercase letter and not have a period at the end of a sentence"
There are numerous cases where this is violated in `kubectl/cmd`. This PR is the result of an audit of all source files under `kublet/cmd` and corrects the case of the initial Flag description character.
/sig cli
/kind cleanup
/kind documentation
**Release note**:
```release-note
NONE
```
Automatic merge from submit-queue (batch tested with PRs 47034, 50329)
Fix comments
**What this PR does / why we need it**:
**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**:
**Release note**:
```release-note
NONE
```
