Inconsistent naming recommendation for XRD kind

### URL
https://docs.crossplane.io/latest/composition/composite-resource-definitions/#xrd-names

### What's Wrong?

In Crossplane v2 there are no more claims, so there's no longer a need to add an "X" prefix to differentiate claims from XRs. The v2 docs were updated to reflect this in 66ca4102982e7e6dda91596ae0c114de326b104b etc., but the XRD page still documents the old naming recommendation, and also does so in an inconsistent manner.

Specifically, this needs to be updated:
https://github.com/crossplane/docs/blob/15fb38a6c4fe6f8b5f6094372f2ff64d4ef3d2d0/content/v2.1/composition/composite-resource-definitions.md?plain=1#L120-L123

As well as examples throughout the page.