Update deployments-loadbalancing.md : remove -f option deletion wild-…

…cards

Error when running:
```
$ kubectl delete -f *.yaml
error: when paths, URLs, or stdin is provided as input, you may not specify resource arguments as well
```
works:
```
$ kubectl delete *.yaml
error: the server doesn't have a resource type "backend-deployment"
```

deployments-loadbalancing.md

@@ -453,7 +453,7 @@ kubectl delete -f frontend-svc.yaml
 kubectl delete -f backend-svc.yaml
 ```
 
-> :bulb: If you ever want to delete all resources from a particular directory, you can use a shell wildcard: `kubectl delete -f *.yaml` which will point at **all** `.yaml` files in that directory!
+> :bulb: If you ever want to delete all resources from a particular directory, you can use a shell wildcard: `kubectl delete *.yaml` which will point at **all** `.yaml` files in that directory!
 
 # Extra Exercise