fix server describe command usage

Author: GokceGK

docs/stackit_beta_server_describe.md

@@ -7,7 +7,7 @@ Shows details of a server
 Shows details of a server.
 
 ```
-stackit beta server describe [flags]
+stackit beta server describe SERVER_ID [flags]
 ```
 
 ### Examples

internal/cmd/beta/server/describe/describe.go

@@ -32,7 +32,7 @@ type inputModel struct {
 
 func NewCmd(p *print.Printer) *cobra.Command {
 	cmd := &cobra.Command{
-		Use:   "describe",
+		Use:   fmt.Sprintf("describe %s", serverIdArg),
 		Short: "Shows details of a server",
 		Long:  "Shows details of a server.",
 		Args:  args.SingleArg(serverIdArg, utils.ValidateUUID),