📖 Add CAPI Operator Quickstart

[dtzar]

What this PR does / why we need it:

Creates a new quickstart path for using the CAPI Operator instead of clusterctl

Fixes #9473

/area documentation

[fabriziopandini]

sgtm, let's squash and wait for some other opinion

[sbueringer]

Thx!

/lgtm
(merge/approve pending squash)

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 90f19a03345b95dca913f3ef0f214c5cb192b6c7

[alexander-demicev]

@dtzar Thanks for taking care of that!

[dtzar]

Some improvements I think we can make, but they will be in the embedded article so this IMO should be good to merge.

[CecileRobertMichon]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: CecileRobertMichon

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[furkatgofurov7]

Hey folks, any objections to backporting this PR?

As per our policy IMO, it is allowed to backport such doc changes?

[sbueringer]

We usually backport all book changes to the last release branch so that they actually show up in the book on https://cluster-api.sigs.k8s.io/ - so yes

/cherry-pick release-1.5

[k8s-infra-cherrypick-robot]

@sbueringer: new pull request created: #9722

In response to this:

We usually backport all book changes to the last release branch so that they actually show up in the book on https://cluster-api.sigs.k8s.io/ - so yes

/cherry-pick release-1.5

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