Update references to `v1beta1` CAPI contract

[salasberryfin]

Description

Some of the examples in the docs still reference CAPI v1beta1 resources. This should be updated to v1beta2 as a continuation of the Turtles/CAPRKE2 CAPI migration.

[anmazzotti]

Note: it would also be best to align the Cluster definitions to what we are currently using on e2e tests.
This includes:

• Kubernetes version used. See: https://github.com/rancher/turtles/blob/main/test/e2e/config/operator.yaml
• Amount of replicas used for control planes/workers. See: https://github.com/rancher/turtles/blob/main/test/e2e/suites/import-gitops/import_gitops_test.go