🌱 Allow generating api-docs for individual versions

[mdbooth]

This change creates separate targets for individual API targets when generating api documentation. The generate-api-docs target continues to execute all of them as before.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mdbooth

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

The pull request process is described here

Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/kubernetes-sigs/cluster-api-provider-openstack/blob/main/OWNERS)~~ [mdbooth] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[netlify[bot]]

✅ Deploy Preview for kubernetes-sigs-cluster-api-openstack ready!

Name	Link
🔨 Latest commit	1734ebbc188dd64cb4f98eb921d4e5dfa231d8ec
🔍 Latest deploy log	https://app.netlify.com/sites/kubernetes-sigs-cluster-api-openstack/deploys/65e8bf9329b52100096fdbcf
😎 Deploy Preview	https://deploy-preview-1929--kubernetes-sigs-cluster-api-openstack.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[huxcrux]

/lgtm