fix typo "udp" -> "UDP"

pkg/kubectl/cmd/expose/expose.go

@@ -74,7 +74,7 @@ var (
 		kubectl expose service nginx --port=443 --target-port=8443 --name=nginx-https
 
 		# Create a service for a replicated streaming application on port 4100 balancing UDP traffic and named 'video-stream'.
-		kubectl expose rc streamer --port=4100 --protocol=udp --name=video-stream
+		kubectl expose rc streamer --port=4100 --protocol=UDP --name=video-stream
 
 		# Create a service for a replicated nginx using replica set, which serves on port 80 and connects to the containers on port 8000.
 		kubectl expose rs nginx --port=80 --target-port=8000