docs: use apiextensions.crossplane.io/v2 for XRD in v2 docs

[kruthiwusirika5]

In Crossplane v2, CompositeResourceDefinition (XRD) apiVersion v1 is deprecated. Update v2.0, v2.1, v2.2 and master doc content to show apiextensions.crossplane.io/v2 for all XRD YAML examples and kubectl describe output. Leaves migration/upgrade doc v1 examples unchanged.

Fixes #1037

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[kruthiwusirika5]

This PR is ready for review when someone has time.

Summary: Fixes a broken reference-style link in the v1.20 multi-tenant guide. The markdown had [Open Policy Agent] (OPA) (space between ] and (), so the link didn’t resolve to the URL defined at the bottom of the file. Removed the space so [Open Policy Agent] correctly uses the reference.

Netlify deploy preview is ready to verify the fix. One-file change.

[kruthiwusirika5]

This PR is ready for review when someone has time.

Summary: Fixes #1037. In Crossplane v2, CompositeResourceDefinition (XRD) apiVersion v1 is deprecated. This updates the v2.0, v2.1, v2.2, and master doc content to use apiextensions.crossplane.io/v2 for all XRD YAML examples and kubectl describe output. Migration/upgrade docs keep their v1 examples unchanged so they still reflect the prior API.

Netlify deploy preview is ready to verify. Happy to adjust if anything should stay on v1.