fix: Improve coder list and show CLI help (#3167)

cli/list.go

@@ -15,14 +15,13 @@ import (
 )
 
 func list() *cobra.Command {
-	var (
-		columns []string
-	)
+	var columns []string
 	cmd := &cobra.Command{
 		Annotations: workspaceCommand,
 		Use:         "list",
 		Short:       "List all workspaces",
 		Aliases:     []string{"ls"},
+		Args:        cobra.ExactArgs(0),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			client, err := createClient(cmd)
 			if err != nil {

cli/show.go

@@ -10,7 +10,7 @@ import (
 func show() *cobra.Command {
 	return &cobra.Command{
 		Annotations: workspaceCommand,
-		Use:         "show",
+		Use:         "show <workspace>",
 		Short:       "Show details of a workspace's resources and agents",
 		Args:        cobra.ExactArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {