docs: short aliases [ci skip]

cli/app/undeploy.go

@@ -13,8 +13,14 @@ import (
 )
 
 var appUndeployCommand = &cli.Command{
-	Name:  "undeploy",
-	Usage: "Undeploy an app",
+	Name:    "undeploy",
+	Aliases: []string{"u"},
+	Usage:   "Undeploy an app",
+	Description: `
+This does not destroy any of the application data. However, you should remain
+vigilant, as your swarm installation will consider any previously attached
+volumes as eligiblef or pruning once undeployed.
+`,
 	Action: func(c *cli.Context) error {
 		appName := c.Args().First()
 		if appName == "" {