docs(fake-client): clarify json-patch version usage

Maintain json-patch v4 to align with Kubernetes code and avoid breaking
changes in v5. This ensures compatibility and stability as the fake client
code is adapted from client-go's testing fixture, which relies on v4.

See:
  - kubernetes/kubernetes#91622
  - kubernetes/kubernetes#120326

Author: kersten

pkg/client/fake/client.go

@@ -29,7 +29,19 @@ import (
 	"sync"
 	"time"
 
-	// Using v4 to match upstream
+	/*
+	  Stick with gopkg.in/evanphx/json-patch.v4 here to match
+	  upstream Kubernetes code and avoid breaking changes introduced in v5.
+	  - Kubernetes itself remains on json-patch v4 to avoid compatibility issues
+	    tied to v5’s stricter RFC6902 compliance.
+	  - The fake client code is adapted from client-go’s testing fixture, which also
+	    relies on json-patch v4.
+	  See:
+	    https://github.com/kubernetes/kubernetes/pull/91622 (discussion of why K8s
+	    stays on v4)
+	    https://github.com/kubernetes/kubernetes/pull/120326 (v5.6.0+incompatible
+	    missing a critical fix)
+	*/
 	jsonpatch "gopkg.in/evanphx/json-patch.v4"
 	appsv1 "k8s.io/api/apps/v1"
 	authenticationv1 "k8s.io/api/authentication/v1"
@@ -1138,7 +1150,7 @@ func (c *fakeClient) deleteObjectLocked(gvr schema.GroupVersionResource, accesso
 		}
 	}
 
-	//TODO: implement propagation
+	// TODO: implement propagation
 	return c.tracker.Delete(gvr, accessor.GetNamespace(), accessor.GetName())
 }