Update KubeOne documentation

[xmudrii]

What this PR does / why we need it:

This PR updates the KubeOne documentation to reflect changes made in #390.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
xref #259

Release note:

NONE

/assign @kron4eg

[kron4eg]

/lgtm
/approve

[kubermatic-bot]

LGTM label has been added.

Git tree hash: 6fbdd3c506d4191723102e8b8e0af69735ef2f22

[kubermatic-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kron4eg

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [kron4eg]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[kubermatic-bot]

@xmudrii: The following test failed, say /retest to rerun them all:

Test name	Commit	Details	Rerun command
pull-kubeone-e2e-aws-conformance-1.13.5	ed9696b	link	/test pull-kubeone-e2e-aws-conformance-1.13.5

Full PR test history

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.

[xmudrii]

/override pull-kubeone-e2e-aws-conformance-1.13.5
docs change only

[kubermatic-bot]

@xmudrii: Overrode contexts on behalf of xmudrii: pull-kubeone-e2e-aws-conformance-1.13.5

In response to this:

/override pull-kubeone-e2e-aws-conformance-1.13.5
docs change only

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.