Ensure consistency in API comments

In our [API](https://github.com/Kuadrant/dns-operator/tree/main/api/v1alpha1), we seem to have a mixture of upper- and lower-case variable names in comments.

It should be consistent. To consider: go docs want capitalisation to match vars (upper case), but when used in other [docs](https://github.com/Kuadrant/dns-operator/pull/488#discussion_r2218541494), it looks strange.

Let's try and make a consistent style in [DNS-Operator]((https://github.com/Kuadrant/dns-operator/tree/main/api/v1alpha1) and [Kuadrant-operator](https://github.com/Kuadrant/kuadrant-operator/tree/main/api/v1alpha1)

Once we have formatted our API docs to be consistent bring this to the kuadrant community to discuss using the same standard elsewhere in the project.

Inspect the Go API comments under api/v1alpha1 in DNS-Operator and the corresponding api/v1alpha1 in Kuadrant-operator, starting with the capitalization examples described in the issue and the linked discussion. Compare the existing style across both repositories, then document the agreed consistent wording and bring the broader standard to the Kuadrant community for discussion.

Written by the indexing model from the issue text.