📖 fix helm install instructions

[rbjorklin]

What this PR does / why we need it:
The docs changes were missed in #638 and later requested by @furkatgofurov7 here.

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 #788

[k8s-ci-robot]

Hi @rbjorklin. Thanks for your PR.

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[furkatgofurov7]

Thank you!

/ok-to-test
/approve
/lgtm
/cherry-pick release-0.19

[k8s-infra-cherrypick-robot]

@furkatgofurov7: once the present PR merges, I will cherry-pick it on top of release-0.19 in a new PR and assign it to you.

In response to this:

Thank you!

/ok-to-test
/approve
/lgtm
/cherry-pick release-0.19

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-sigs/prow repository.

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: a6393aa1b335647b595db405e134461c939e58d1

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: furkatgofurov7

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• OWNERS [furkatgofurov7]

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[k8s-infra-cherrypick-robot]

@furkatgofurov7: new pull request created: #797

In response to this:

Thank you!

/ok-to-test
/approve
/lgtm
/cherry-pick release-0.19

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-sigs/prow repository.