🌱 Update examples & code snippets in Cluster API book to v1beta2 for ClusterClass

[sivchari]

What this PR does / why we need it:

Part of #12448

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 #

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign joelspeed for approval. For more information see the Code Review Process.

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

Needs approval from an approver in each of these files:

• OWNERS

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

[k8s-ci-robot]

This PR is currently missing an area label, which is used to identify the modified component when generating release notes.

Area labels can be added by org members by writing /area ${COMPONENT} in a comment

Please see the labels list for possible areas.

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.

[fabriziopandini]

Thanks for this PR!
Could you kindly check the list of ClusterClass fields in https://main.cluster-api.sigs.k8s.io/tasks/experimental-features/cluster-class/change-clusterclass#effects-on-the-clusters (some of the fields name have been changed)

[sbueringer]

There are also some more changes coming in via: #12489, sorry.
(please check the diff in clusterclass_types.go)