fix: scope API compatibility statement to tested Kubernetes versions and required capabilities

Author: augustrh

cncf/GTR.md

@@ -183,8 +183,10 @@
 
     * **Describe compatibility of any new or changed APIs with API servers, including the Kubernetes API server**
 
-      All OCM APIs are implemented as standard Kubernetes CRDs, ensuring full compatibility with any conformant Kubernetes API server.
-      We maintain compatibility with Kubernetes versions from 1.24+ and test against multiple Kubernetes distributions.
+      All OCM APIs are implemented as standard Kubernetes CRDs. OCM is tested against Kubernetes 1.24 and newer and
+      requires a Kubernetes API server with support for CRDs, CertificateSigningRequests, and RBAC. Compatibility
+      is validated against multiple Kubernetes distributions as part of the release process; versions or distributions
+      outside this tested range are not guaranteed to work.
 
     * **Describe versioning of any new or changed APIs, including how breaking changes are handled**