options, kube-apiserver: clarify scheme on etcd endpoints

[gyuho]

What this PR does / why we need it:

Fix typo in kube-apiserver flag.

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

None

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This change is

[k8s-ci-robot]

Can a kubernetes member verify that this patch is reasonable to test? If so, please reply with "@k8s-bot ok to test" on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands will still work. Regular contributors should join the org to skip this step.

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[nikhiljindal]

LGTM, thx!
I dont think we need a release note for this.

[gyuho]

@nikhiljindal Agree. Just left release note empty. Thanks!

[saad-ali]

Release-czar approved post-code freeze merge--This was LGTMed and in the merge-queue at code freeze time for 1.5. Adding 1.5 milestone to let it gets merged after code freeze.

[k8s-github-robot]

Automatic merge from submit-queue