docs: expand deploy/upgrade/downgrade docs

cli/app/rollback.go

@@ -26,6 +26,13 @@ var appRollbackCommand = &cli.Command{
 	},
 	Description: `
 This command rolls an app back to a previous version if one exists.
+
+You may pass "--force/-f" to downgrade to the same version again. This can be
+useful if the container runtime has gotten into a weird state or your doing
+some live hacking.
+
+This action could be destructive, please ensure you have a copy of your app
+data beforehand - see "abra app backup <app>" for more.
 `,
 	BashComplete: func(c *cli.Context) {
 		appNames, err := config.GetAppNames()