docs: pass on sub-command help

cli/server/prune.go

@@ -31,13 +31,12 @@ var volumesFilterFlag = &cli.BoolFlag{
 var serverPruneCommand = cli.Command{
 	Name:    "prune",
 	Aliases: []string{"p"},
-	Usage:   "Prune a managed server; Runs a docker system prune",
+	Usage:   "Prune resources on a server",
 	Description: `
 Prunes unused containers, networks, and dangling images.
 
-If passing "-v/--volumes" then volumes not connected to a deployed app will
-also be removed. This can result in unwanted data loss if not used carefully.
-	`,
+Use "-v/--volumes" to remove volumes that are not associated with a deployed
+app. This can result in unwanted data loss if not used carefully.`,
 	ArgsUsage: "[<server>]",
 	Flags: []cli.Flag{
 		allFilterFlag,