added flag to have a custom text on the USAGE section of help

command.go

@@ -16,6 +16,8 @@ type Command struct {
 	Aliases []string
 	// A short description of the usage of this command
 	Usage string
+	// Custom text to show on USAGE section of help
+	UsageText string
 	// A longer explanation of how the command works
 	Description string
 	// A short description of the arguments of this command

help.go

@@ -15,7 +15,7 @@ var AppHelpTemplate = `NAME:
    {{.Name}} - {{.Usage}}
 
 USAGE:
-   {{.HelpName}} {{if .Flags}}[global options]{{end}}{{if .Commands}} command [command options]{{end}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}[arguments...]{{end}}
+   {{if .UsageText}}{{.UsageText}}{{else}}{{.HelpName}} {{if .Flags}}[global options]{{end}}{{if .Commands}} command [command options]{{end}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}[arguments...]{{end}}{{end}}
    {{if .Version}}
 VERSION:
    {{.Version}}