kubeadm: fix godocs indentation for v1beta1

[neolit123]

What this PR does / why we need it:
fix for a previous PR that the indentation of godocs page was wrong.
adds \t in front of all lines to make them a part of a list as, godocs does not support bullets.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
NONE

Special notes for your reviewer:
NONE

Does this PR introduce a user-facing change?:

NONE

/priority important-soon
/assign @timothysc @fabriziopandini
/kind documentation
/sig cluster-lifecycle

[timothysc]

/approve
/lgtm
/hold

Did you verify locally? If so, feel free to cancel the hold.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: neolit123, timothysc

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[neolit123]

Did you verify locally? If so, feel free to cancel the hold.

yes this time i did.

/hold cancel

[neolit123]