docs: add minimum versions to the command pages

cmd/help.go

@@ -33,6 +33,9 @@ See the home page (https://rclone.org/) for installation, usage,
 documentation, changelog and configuration walkthroughs.
 
 `,
+	Annotations: map[string]string{
+		"versionIntroduced": "v0.90",
+	},
 	PersistentPostRun: func(cmd *cobra.Command, args []string) {
 		fs.Debugf("rclone", "Version %q finishing with parameters %q", fs.Version, os.Args)
 		atexit.Run()