build, node: fix go vet nits

build/update-license.go

@@ -185,7 +185,7 @@ func getFiles() []string {
 		files = append(files, line)
 	})
 	if err != nil {
-		log.Fatalf("error getting files:", err)
+		log.Fatal("error getting files:", err)
 	}
 	return files
 }

node/node_example_test.go

@@ -41,7 +41,7 @@ func (s *SampleService) APIs() []rpc.API           { return nil }
 func (s *SampleService) Start(*p2p.Server) error   { fmt.Println("Service starting..."); return nil }
 func (s *SampleService) Stop() error               { fmt.Println("Service stopping..."); return nil }
 
-func ExampleUsage() {
+func ExampleService() {
 	// Create a network node to run protocols with the default values. The below list
 	// is only used to display each of the configuration options. All of these could
 	// have been omitted if the default behavior is desired.