Add target components on check_readme_versions.sh (#9045)

This adds target components on check_readme_versions.sh after
merging https://github.com/kubernetes-sigs/kubespray/pull/9044
In addition, this fixes typo on check_readme_versions.sh

This adds `foo_version` variables for some components because
check_readme_versions.sh verifies the corresponding version for
`<component name>_version` from main.yml. This change also makes
consistency in the main.yml. In long-term, we will be able to
remove the existing `foo_image_tag` variables, but that is not now
for backwards compatibility for users.