Simplify event recording example

There is no need for `fmt.Sprintf` since `EventRecorder` already has `Eventf` method that accepts formatting string

Author: rkosegi

docs/book/src/reference/raising-events.md

@@ -33,10 +33,9 @@ Following is an example of a code implementation that raises an Event.
 
 ```go
 	// The following implementation will raise an event
-	r.Recorder.Event(cr, "Warning", "Deleting",
-		fmt.Sprintf("Custom Resource %s is being deleted from the namespace %s",
-			cr.Name,
-			cr.Namespace))
+	r.Recorder.Eventf(cr, "Warning", "Deleting",
+		"Custom Resource %s is being deleted from the namespace %s",
+		cr.Name, cr.Namespace)
 ```
 
 </aside>
@@ -110,4 +109,4 @@ And then, run `$ make manifests` to update the rules under `config/rbac/role.yam
 [Event-Example]: https://github.com/kubernetes/api/blob/6c11c9e4685cc62e4ddc8d4aaa824c46150c9148/core/v1/types.go#L6019-L6024
 [Reason-Example]: https://github.com/kubernetes/api/blob/6c11c9e4685cc62e4ddc8d4aaa824c46150c9148/core/v1/types.go#L6048
 [Message-Example]: https://github.com/kubernetes/api/blob/6c11c9e4685cc62e4ddc8d4aaa824c46150c9148/core/v1/types.go#L6053
-[rbac-markers]: ./markers/rbac.md
+[rbac-markers]: ./markers/rbac.md