[Web Bug] - Composite Resource Definitions documentation are missing categories

* As a XRD author,
* in order to help management of the claims and xr custom resources
* I need to specify categories in XRD for claims and XRs

However, categories support in XRD are not documented, and only appear in the XRD openapi schema

URL: https://docs.crossplane.io/v2.3/composition/composite-resource-definitions/

https://github.com/crossplane/crossplane/blob/56aace77e6771894afa157a3339dbe8d6d15401a/cluster/crds/apiextensions.crossplane.io_compositeresourcedefinitions.yaml#L66-L81
```yaml
claimNames:
description: |-
ClaimNames specifies the names of an optional composite resource claim.
...
properties:
categories:
description: |-
categories is a list of grouped resources this custom resource belongs to (e.g. 'all').
This is published in API discovery documents, and used by clients to support invocations like
`kubectl get all`.
```

Likewise, guidance to crossplane users on use of naming of categories would be useful to provide a good user experience. See related feedback upstream at https://github.com/kubernetes/website/issues/56279