Exclude hidden sub-command flags from docs

docs.go

@@ -80,14 +80,14 @@ func prepareCommands(commands []*Command, level int) []string {
 			usageText,
 		)
 
-		flags := prepareArgsWithValues(command.Flags)
+		flags := prepareArgsWithValues(command.VisibleFlags())
 		if len(flags) > 0 {
 			prepared += fmt.Sprintf("\n%s", strings.Join(flags, "\n"))
 		}
 
 		coms = append(coms, prepared)
 
-		// recursevly iterate subcommands
+		// recursively iterate subcommands
 		if len(command.Subcommands) > 0 {
 			coms = append(
 				coms,

docs_test.go

@@ -103,6 +103,11 @@ Should be a part of the same code block
 					Aliases: []string{"s"},
 					Usage:   "some usage text",
 				},
+				&StringFlag{
+					Name:   "sub-command-hidden-flag",
+					Usage:  "some hidden usage text",
+					Hidden: true,
+				},
 			},
 			Name:      "sub-usage",
 			Usage:     "standard usage text",

fish.go

@@ -95,7 +95,7 @@ func (a *App) prepareFishCommands(commands []*Command, allCommands *[]string, pr
 		completions = append(completions, completion.String())
 		completions = append(
 			completions,
-			a.prepareFishFlags(command.Flags, command.Names())...,
+			a.prepareFishFlags(command.VisibleFlags(), command.Names())...,
 		)
 
 		// recursevly iterate subcommands