docs: add minimum versions to the command pages

cmd/serve/ftp/ftp.go

@@ -99,6 +99,9 @@ By default this will serve files without needing a login.
 
 You can set a single username and password with the --user and --pass flags.
 ` + vfs.Help + proxy.Help,
+	Annotations: map[string]string{
+		"versionIntroduced": "v1.44",
+	},
 	Run: func(command *cobra.Command, args []string) {
 		var f fs.Fs
 		if proxyflags.Opt.AuthProxy == "" {