Updated help usage test (#13)

Author: joshdk

.github/workflows/main.yml

@@ -16,7 +16,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@master
+        uses: actions/checkout@v1
 
       - name: Setup go
         uses: actions/setup-go@v1

main.go

@@ -41,6 +41,7 @@ func mainCmd() (bool, error) {
 	flag.DurationVar(&spec.Sleep, "sleep", 5*time.Second, "time to sleep between attempts")
 	flag.DurationVar(&spec.TaskTime, "task-time", 0, "maximum time for a single attempt")
 	flag.BoolVar(&versionFlag, "version", false, fmt.Sprintf("print the version %q and exit", version))
+	flag.Usage = usage
 	flag.Parse()
 
 	// If the version flag (-version) was given, print the version and exit.
@@ -79,3 +80,8 @@ func mainCmd() (bool, error) {
 		return false, nil
 	}
 }
+
+func usage() {
+	fmt.Fprintf(flag.CommandLine.Output(), "Usage: retry [flags] command|url\n")
+	flag.PrintDefaults()
+}