Commonly used CRDs in a format that kubeval/kubeconform can use.
kubeval --strict --additional-schema-locations https://raw.githubusercontent.com/dmichel1/kube-crds/master kube-resources.yaml
Schema files were created based on the script in the kubeconform repo.
Make sure to run with export FILENAME_FORMAT='{kind}-{group}-{version}'. Schema files should be in both -strict and non-strict directories.